Breaking Plumbing on Windenburg Lot
I downloaded the lot and as far as I can tell, nothing wrong with it. Only thing I would change that might have something to do with your mischief issue is change the Convival lot trait to something else so that mischief is not encouraged or made easier.
On the club, find the leader of the Renegades to change the club activities. There is no mod that I know of that will let you change them. You have to play the leader so you can get to club configuration panel. I don't remember who the leader is for that club as it's long gone from my game. But you do know that Wolfgang Munch (shown in your pic) is a member so play his household in Windenberg and look in his club panel to see who the leader is. I do remember that Morgan Fryes is another member so you could use her too. Once you know who the leader is, then play their household and use their club panel to change the club activities to remove any mischief related or other activities that they do that you don't like.
From your pic, it is clear that there is a club meeting in progress. I don't remember where their meeting place is but it appears that it was probably the lot you used for your gym. You probably ought to change their meeting place so the club doesn't frequent your gym and their meeting place is somewhere else when you do edit the club configuration panel of the leader.
Hope this helps.
