Have that shit too at times, although maybe not as bad as yours. The only means I've learnt to cope with them is to just brush it off. They are a part of me, but they're not me. So, I accept them, but don't take them too serious. They're usually quite predictable anyway and sometimes I ridicule them for lack of creativity. Can laugh at them too when they're funny.
Tourette's sufferers come to mind. Everyone thinks they are these rude, racist, whathaveyou people. But really if they make such remarks it proves they're actually good people underneath, because their mind will say the worst it can think of. But if they suppress these thoughts it gets worse and almost unbearable to keep them in. Maybe this can help you a bit.
As for your question, a secluded bog, a deserted mineshaft or volcano comes to mind. Most simple and reliable is probably letting wild animals take care of it. So, as you mentioned the ocean is good or maybe a deep forest, basically anything with carnivores or insects. A crocodile pit, too. Humid heat should also speed up the process.