pse@Mithos:~$ touch /tmp/foo
pse@Mithos:~$ sudo chflags schg /tmp/foo
pse@Mithos:~$ rm /tmp/foo
override rw-r--r--  pse/wheel schg for /tmp/foo? yes
rm: /tmp/foo: Operation not permitted
pse@Mithos:~$ sudo chflags noschg /tmp/foo
pse@Mithos:~$ rm /tmp/foo
pse@Mithos:~$ ll /tmp/foo
ls: /tmp/foo: No such file or directory