Message overloading.

I do not go to chess.com daily and I have 50 groups, I also have 4000 messages, can somebody tell me how to wipe 'em out? I can just keep clicking ignore, or read and ignore, or check off 25 that I want to delete but they will all take atleast 5 hours (my computer lags a LOT)! If there is no way, I can't read my messages again-NOT GOOD!