The month or two thing will work for some exposures, but the bummer reality is that these sites are terrible and the worst of them take persistence and escalation to remove, which can take some time.
(I've been working for one of the aforementioned—Kanary—for about a year now on this sort of thing.)
Re: undoing opt-outs, we do not do that, but data brokers will re-surface your information again if they find it elsewhere.
