How to create a list of files without their extensions in python 3

Question

I got lost when trying to get a list of files but without their extension. I am getting the a list of files in this specific directory using:

files = os.listdir("C:/Users/sp500/")

All files are with ".csv" extension which I would like to remove (I need the list of tickers only).

Using strip as suggested here and here (I am getting this error: TypeError: expected str, bytes or os.PathLike object, not list) doesn't help nor other remove function etc. I will appreciate your help very much!