Personally, I think that @Jon Clements' answer is very suitable if you are working with numbers, but here is a generic option:

start_index = 1  
n = 5

arr = list(range(50))
arr[start_index::n] = None
elem= [elem for elem in arr if elem is not None]

This uses list slicing to set every nth element (elem) in a list to None, and then uses list comprehension to only retain elements that are not assigned None in the list. The initial value of the list (arr) is an arbitrary list of numbers between 0 (inclusive) and 50 (exclusive).

Using a list comprehension is not particularly efficient, but this will work in the case when you cannot (for some reason) use external libraries, or if the elements of your list are not numeric (although there are better options).