Though I was never banned from a gym, I did have something similar happen to me as a senior in high school. I had co-coached a Pop Warner team in my area for three years, it was my younger sister's team. I was a cheerleader at the same time that I coached, and I attended tumbling classes with a tumbling coach who taught many girls in my area. I often advocated the girls on the team I coached who had issues with their tumbling to go to her, and I was also good 'friends' with her. The point of my story is: a woman who was the mother of one of the girls I coached got into an argument of sorts with my tumbling coach, I'm not sure what exactly went down, but it involved possible lawsuits. Immediately after that drama, I got a nasty e-mail from this woman, who was now apparently the head of the Pop Warner organization I coached for, telling me I was being replaced and I was never to attend a practice or game again, let alone step foot on the Pop Warner 'property'. This woman actually BCC'd the e-mail she sent me to all possible cheer coaches in the organization (football and cheer) to make sure I did not coach on ANY team. In her e-mail she cited her reason being that there were "complaints" against me, which is odd since I never once raised my voice at my team, volunteered 15+ hours a week to coach them, organized routines, ordered their custom clothing (which I ended up paying $90 out of pocket for!), and hand made all 37 of their bows, all while I was in high school and had a team of my own! Needless to say, my parents and I were outraged. My father politely e-mailed her asking for the exact 'complaints' against me, though she never replied.
Though this took place over two years ago, I am still to this day amazed how childish an adult woman could be.