Delete Previous App Purchases

I want to be able to completely delete (not hide or remove) previous app purchases. Reason being is that I recently set up screen time controls for my child’s iphone. There are apps that he shouldn’t have but already downloaded before I set up the controls. I have it set up now so that new app purchases/downloads require approval, but the ones that he installed in the past, download without the approval prompt and I’m thinking it’s because he already downloaded them in the past. Any ideas out there?