You do not need PHP to do any of this for you. SQL is capable of deleting any record where neither newsletter is selected. You can specify any number of where clauses.
DELETE FROM newsletters WHERE mens = 0 AND womens = 0
Alternatively, the structure of the table can be modified so that the newsletter type and the email are the only two keys, both of which create a composite key. Having a record means they subscribe to at least one, no records mean they subscribe to neither. Seems a little overboard to do that IMO.