app lockdown

You may find this information to be helpful with setting-up an AppleID for a minor - and considering appropriate controls:

Apple for Kids - Official Apple Support

Help your child set up an iPhone, iPad, or iPod touch - Apple Support

Family Sharing and Apple ID for your child – Apple Support

Use parental controls on your child's iPhone, iPad and iPod touch – Apple Support

First of all, delete the apps.

Delete apps on your iPhone, iPad, and iPod touch - Apple Support.

Next, hide the purchases of the apps. This will prevent your child redownloading them from iCloud.

Hide purchases from the App Store - Apple Support

Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support

Also- if your child knows the password to the iPad's apple id, change it.