How can I block and app I previously approved?

Androids allows you to, with 1 click, block, disable, restrict or uninstall an app from a childs device. RoBlox is consuming my son's life and sexual content is making its way into this game. I want my son OFF this game. There is no way to stop him (other than me taking a hammer to the device) from re-installing the game!

This is utterly unacceptable. Android I can click 1 button and LOCK all of his devices at the same time.

I have added a 1 minute time limit to this game and it is not respected as the All Apps 2.5 hour limit takes over. and even somehow that is not taking place. I dont know HOW he spent 7 hours on this device last night when I have it LOCK. he does not know the passcode.

I have taken the device away from him until I solve this. It's amazing he went outside and climbed a tree. PARENTS TAKE NOTE - APPLES WANTS YOUR KIDS ON DEVICES! mine is outside as I type this, playing like kid should.