Remove item from List and get the item simultaneously

public static class ListExtensions
{
  public static T RemoveAndGetItem<T>(this IList<T> list, int iIndexToRemove}
  {
    var item = list[iIndexToRemove];
    list.RemoveAt(iIndexToRemove);
    return item;
  } 
}

These are called extension methods, call as new List<T>().RemoveAndGetItem(0).

Things to consider in the extension method

Exception handling with the index that you pass, check that the index is withing 0 and the count of the list before doing this.

No, as it's a breach of pure function etiquette, where a method either has a side effect, or returns a useful value (i.e. not just indicating an error state) - never both.

If you want the function to appear atomic, you can acquire a lock on the list, which will stop other threads from accessing the list while you are modifying it, provided they also use lock:

public static class Extensions
{
    public static T RemoveAndGet<T>(this IList<T> list, int index)
    {
        lock(list)
        {
            T value = list[index];
            list.RemoveAt(index);
            return value;
        }
    }
}