I wouldn't necessarily call any of the following cancelations per se, bc it's not like everybody and their mother started to hate me for them, but I've had plenty of altercations.
Facebook: maybe a couple, three times for differing opinions
Instagram: never, but I have been DM'd several times by celeb imposters
Twitter: so many times that I rarely ever go on anymore, except for selca days
YouTube: several times, mostly for misinterpreting comments as rude/insensitive/etc.
KPS: twice bc I couldn't keep my mouth shut
Other forums:
-I was told to die on a general music interest forum back in 2005 bc I admitted to being a Simple Plan fan (at the time, not anymore), and I either quit or got banned bc of this (I don't remember which)
-I was bullied several times on a forum for fans of a (now defunct) band called The Click Five
-same thing on the old 1D forums (only by trolls, though - despite the nontoxicity otherwise, it wasn't a very well-moderated forum)