for to_delete in keys_to_delete:
# need to check if is present - can not delete a key which does not exist in dictionary
if to_delete in phones:
del phones[to_delete]
print(phones)
or alternatively you can use pop
method with a default value
for to_delete in keys_to_delete:
phones.pop(to_delete, None) # returns None if key not present
print(phones)