Python – "PermissionError [WinError5] – access denied", when removing files [duplicate]

I made a python function, that checks whether a flash USB is inserted and if yes, it deletes all files from the USB.

using OS module here

import os

def clean_USB():
        os.chdir("F:") # change directory to F: (USB in this case)

    except FileNotFoundError: # "FileNotFoundError" when the program didn't find that directory
            retry = input("USB flash is not inserted. Insert USB and press [ENTER] to try again or [CTRL + C] to exit: ")
            clean_USB() # run the funtion again (look for F:) if the user retried. 

        except KeyboardInterrupt: # [Ctrl + C] = "KeyboardInterrupt"
            quit() # close the program otherwise

    if os.listdir() != []: # if the list of all files in USB directory is not an empty list 
        for deletable_file in os.listdir(): # get every file from directory
            os.remove(deletable_file) # delete that file
        print("nPrevious PDF files are deleted from USB.") # send message

        print("nUSB flash is already empty.")

But I get an error:

PermissionError: [WinError5] Access denied '$RECYCLE BIN'

I serached about this a little and couldn’t find how to solve the problem, when the program deletes files…

Thank you for any help!

Source: Windows Questions