When I was buildteam a few years ago I received a free rank upgrade to the highest rank MCC had back then, which was legend. It however glitched out in the minigames so I kept the Bedrock rank I already had (on the subservers I had legend). I personally dislike the aesthetic of the Legend rank and would like to go back to my Bedrock rank. I don't want to receive back any money or anything since it was a free upgrade anyway. I've heard of people having their rank removed before so I believe it shouldn't be an issue.
Your best shot would be a donation issue email. Instructions on how to fill one in with the proper format can be found here. Hope this helps, and good luck getting that fixed!