What can I do if someone added me to his/her fanlist but I don't want it?

I don't think bạn can. Being on someone's fanlist means that they're a người hâm mộ of you, not that you're a người hâm mộ of them. However, bạn don't have to người hâm mộ them back if bạn don't want to.

Lel i suggest getting a life and caring about such small things like seriously why would bạn care about something like that.? completely ridiculous and unnecessary.

bạn do not have to add them back hoặc anything.

bạn could politely ask them to unfan you, if bạn really don't want it.