That depends on conditions. I'm going to assume since its an ability, I can do it whenever I want. Sooo... I'd probably do some deathnote like shit where I cleanse the world of evil people and go insane or something. Also make a huge landmarks disappear for the lulz. same q
Probably something like "Well fuck you" and then drop them completely. No point in dwelling on the past if someone wants to be an asshole then I will treat them like one, if they want to be nice then I will treat them fairly.