If I use chmod to set the permissions correctly before I try to use shutil.rmtree then it should work. I'm going to test this and provide an update when I know it works.
I can confirm the solution works.
import shutil
import os
src = "/media/device/my_folder"
if os.path.exists(dst):
os.chmod(dst, 0o777)
for root,dirs,_ in os.walk(dst):
for d in dirs :
os.chmod(os.path.join(root,d) , 0o777)
shutil.rmtree(dst)