Help Please- How to reset stat data?

So I bought a new watch for my son and I got the old watch and I did not discount from his phone and went for a run. I am 53 slow runner and he is super fast 17 year old. SO he really upset as I messed up al lhis data such as Vo2 max, aergate hear rate , race perdication and so on. 

We delted my run from hsi Garmin connect account but eveythign is prerty emssed up. Is there a way to restor the old date or forced it to resycn using all his existing activity?