Yes. Three times. No regrets. I hope I never see or hear about them ever again. I don't feel like sharing every detail though. That would take forever.
One contacted me after a decade of ignoring me, just so I could help their friend to settle in the same country I was living in. What irked me was that they were clearly pretending to be very excited to be in touch with me again. Yea right. If they cared for me surely they would have found the time to send a message even if just once every two years, which they didn't... I can understand people growing apart, but I don't tolerate being taken for an idiot.
The other, it took me a long time to realize what a passive aggressive asshole they were. They moved elsewhere, and we lost contact for a while. Then they reached out online, and that's when I realized how much better things were for me without them in my life. So we had a bland chat in which I said the bare minimum, and after that I cut them off.
The other, I would be typing a wall of text to explain what happened. Some prime reddit AITA material. Summarizing, we used to work together at the same place. I covered up for their mistakes (and unexplained absences and missed deadlines) a lot. This put me under a lot of stress. They were also going through a lot of hardship which was totally self inflicted, and against my advice. The situation escalated until I just had to let it go. It's not exactly the reason my contract didn't get renewed, or the only thing making my life difficult at the time, but burnout at work was at the core. I can't help wonder how things would have resolved if I managed to keep a cool head at the moment. What made me burn the bridge was their complete obliviousness to their own blundering afterwards. They learned nothing out of it, and I don't need a second round of that in my life. So bye bye.