So... many.... mean ... comments... I have typed and then deleted.
They're not just being there. They're following you on multiple characters, likely harassing you with tells/trade requests/emotes. Spreading rumors to your FC or LS, possibly NN. There ARE ways to avoid all this but nobody should need to take the full burden of security on themselves. SE should put in SOME concessions so that if you wish to break a contact link with someone you can. Not removing people from a both friend lists when you unfriend them is .. well.. silly. Senn makes a good point that the harassment can follow you outside the game as well, to the forums, discord servers and anything else linked to your character or FC.