If you can use RemoveRange
method, simply do:
list.RemoveRange(index, count);
Where index is where to start from and count is how much to remove. So to remove everything from a certain index to the end, the code will be:
list.RemoveRange(index, list.Count - index);
Conversely, you can use:
list.GetRange(index, count);
But that will create a new list, which may not be what you want.