Removes all elements from the SortedList`2.
SortedList`2.Count is set to zero, and references to other objects from elements of the collection are also released.
SortedList`2.Capacity remains unchanged. To reset the capacity of the SortedList`2, call SortedList`2.TrimExcess or set the SortedList`2.Capacity property directly. Trimming an empty SortedList`2 sets the capacity of the SortedList`2 to the default capacity.
This method is an O(n) operation, where n is SortedList`2.Count.