A very simple and basic script to delete unwanted folders of a very specific type, in this case, .dmg files.

utilitytodeletefiles.py

import os
import fnmatch

CONSTANT_DIRECTORY_TO_CLEAN = "/Users/arkangel/Downloads/"

os.chdir(CONSTANT_DIRECTORY_TO_CLEAN)
# ensure that change to that directory worked
print(os.getcwd())

# just to get an idea of all the files in that directory
listOfFiles = os.listdir('.')

# ok, i want to find all downloaded(and installed) applications not in use Mac(.dmg) Windows(.exe)
pattern = "*.dmg"

# I expect a list, iterate
for entry in listOfFiles:

    # simple find and check that a file, folder or directory matches this pattern
    if fnmatch.fnmatch(entry, pattern):
        # if it matches that pattern, print it
        print(entry)

        # print the title
        print(entry.title())

        # delete it
        os.remove(entry)