Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Removes a range of entries inside an array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The start index where entries will be removed from.</param>
/// <param name="length">The number of entries to be removed.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">index</exception>
public static T[] RemoveRange<T>(this T[] array, int index, int length)
{
    if (length < 1)
    {
        return array;
    }

    if (index < 0 || index > array.Length - 1)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    if (index + length > array.Length - 1)
    {
        Array.Resize(ref array, index);
        return array;
    }

    var endLength = Math.Max(0, Math.Min(array.Length - index, array.Length - (index + length)));
    var tempArray = new T[endLength];
    Array.Copy(array, index + length, tempArray, 0, endLength);
    Array.Resize(ref array, array.Length - length);
    tempArray.CopyTo(array, array.Length - endLength);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Moves the specified entries in the array by a set ammount.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The start index where entries will be moved from.</param>
/// <param name="length">The number of entries to be moved.</param>
/// <param name="shift">The ammount and direction to move the specified entries.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">length;'length' argument must be greater then 0.</exception>
/// <remarks><p>To move entries to the left (towards 0) specify a negative shift value and a positive shift value to move entries to the right.</p>
/// <example>
/// <code>
/// var items = new[] { 0, 1, 2, 3, 4 };
/// items = items.Move(3, 2, -1);
/// </code>
/// Result should be { 0, 1, 3, 4, 4 }
/// </example></remarks>
public static T[] Move<T>(this T[] array, int index, int length, int shift)
{
    if (length <= 0)
    {
        throw new ArgumentOutOfRangeException("length", "'length' argument must be greater then 0.");
    }

    if (shift > 0 && index + length + shift > array.Length - 1)
    {
        Array.Resize(ref array, array.Length + (index + length + shift - array.Length));
    }

    if (index + shift < 0)
    {
        length += index + shift;
        index = -(index + shift);
    }

    length = Math.Min(array.Length - index, length);
    if (length > 0)
    {
        Array.Copy(array, index, array, index + shift, length);
    }        

    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Crops an array to a specified length.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="length">The length that the destination array will be set to.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Crop<T>(this T[] array, int length)
{
    if (array == null)
    {
        return array;
    }

    Array.Resize(ref array, Math.Max(length, 0));
    return array;
}

/// <summary>
/// Crops an array to a specified length.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The index in the destination array where cropping begins at.</param>
/// <param name="length">The length that the destination array will be set to.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">length;'length' argument must be greater then 0.</exception>
public static T[] Crop<T>(this T[] array, int index, int length)
{
    if (array == null)
    {
        return array;
    }

    if (length <= 0)
    {
        throw new ArgumentOutOfRangeException("length", "'length' argument must be greater then 0.");
    }
                 
    if (index < 0 || index > array.Length - 1)
    {
        return array;
    }
                        
    length = Math.Min(length, array.Length - index);
    if (index > 0)
    {
        Array.Copy(array, index, array, 0, length);
    }

    Array.Resize(ref array, length);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Adds the specified source array to the end of the destination array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="sourceArray">The source array that will be added to the end of the destination array.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Add<T>(this T[] array, T[] sourceArray)
{
    if (array == null || sourceArray == null || sourceArray.Length == 0)
    {
        return array;
    }

    Array.Resize(ref array, array.Length + sourceArray.Length);
    sourceArray.CopyTo(array, array.Length - sourceArray.Length);
    return array;
}

/// <summary>
/// Adds a new extry to the end of the destination array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="value">The item that will be added to the end of the destination array.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Add<T>(this T[] array, T value)
{
    if (array == null)
    {
        return array;
    }

    Array.Resize(ref array, array.Length + 1);
    array[array.Length - 1] = value;
    return array;
}