Q: How do I revoke approval of an app once I've given it?  I don't want my kids to be able to download an app I previously approved.

About Restrictions (parental controls) on iPhone, iPad, and iPod touch - https://support.apple.com/HT201304

The restrictions' settings is too broad. We need to be able to choose individual apps to restrict.

The settings are too broad. It doesn't allow us to restrict an individual app.

hey_applebottom wrote:

 

I approved an app that turned out to be awful for my kids.  I now want to revoke approval.  I have deleted it from their phones but they are still able to download and install it.

Read Hide purchases: Hide and unhide iTunes Store, App Store, or iBooks Store purchases - Apple Support

Setup: Settings > General > Restrictions > put in a passcode, don't forget what you do here > Installing Apps: Off

Restrictions is the only way.