Hey Knut and Adam 
So it is possible to do this-there are essentially 2 options.
The easiest way to accomplish this 
is to Delete a Performance. You will want to tap on the “Workouts” tab in the “Workouts” menu, and just select the God performance that you wish to delete.
The far more drastic option is to completely reset your Athlete profile, which erases all training history-essentially giving you an Athlete level of “0”. I think that’s what you are asking here Knut
I really never recommend that we take this step, having a good training history really helps the Coach assign you the right level of sessions, ensuring you make the best progress towards your own training goals. PBs are but one indicator of training progress, and I honestly would focus on the progress you have surely made-in terms of your overall fitness, your mental wellbeing, your diet etc.
