I've been lonely my whole life so I'm pretty good at getting people away from me. If you see them everyday it's pretty hard I think but if you see them sometimes or only message them it's pretty easy.
So if they invit you to go out, start by refusing like 1/4 time, then 1/3 time... till they get tired of asking you to go out. If they message you, just be cold, answer with few words. Eventualy people will get tired of trying and move on with their life.
I'm planning to CTB in 3 years and that's what I'll do. For now I got some close friends but I think I can get away pretty easily in 6 months or so. About my parents it'll be harder, I'll move out pretty far away, find some excuses to not come to birthday and shit like that and just CTB after 6-9 months.
It takes time, people will still be harmed but I think less than if you do it tomorrow without telling anybody.