Correct way to remove addresses from DB

I got from a previous owner a big list of addresses. Some of these addresses are now old, "overquota" or broken. I'd like to simply remove those. But if I mass-unsubscribe those, they will remain in the DB both in simplenews_substriptions (with "activated"==1 !) and in simplenews_snid_tid with "status" == 0 and "source" == "mass unsubscribe".

Is there a standard procedure to remove the addresses?
Or should I just put on some SQL over those 2 tables? (Are there others involved?)

Thanks