Avatar Removal SQL Query

[Morrus]

I'm having a bit of an issue with avatars remaining after a paid subscription expires.

What is the SQL query I would use in the AdminCP to remove all avatars from users not currently in Usergroup X OR Usergroup Y, either primary or secondary?

(in other words, Primary X, Secondary X, Primary Y, and Secondary Y should all keep their avatars, but everybody else should not)?

Second question:

How would I do exactly the same thing for signatures?

Thanks!