Yes its posible but just looking at the piece of code you give me, you don't have the player ID so I'll assume that is not the server who is setting default skills to 10 but the database itself through a TRIGGER, in case that is right your solution is even easier:
Go to your database and go to `players` table, check for "TRIGGERS", you should see oncreate TRIGGER that adds row to player_skills, just edit the values there.