On the device you want to restrict app installing or deleting for:
Open the iOS settings
Click Screen Time
Click Content and Privacy Restrictions
Enter iOS restrictions PIN if it’s been set
Toggle the Content and Privacy Restrictions switch
Click iTunes and App Store Purchases
To block your child’s ability to install apps
Click Installing Apps
To block your child’s ability to delete apps
Click Deleting Apps
To block your child’s ability complete in app purchases
Click In-app Purchases
Click the back arrow next to iTunes and App Store Purchases
Click the back arrow next to Content and Privacy Restrictions
Will this impact my child’s ability to delete or purchase any apps?
Yes, your child will be able to install or remove any apps.
Why doesn’t my child’s device look like that?
You may need to update the operating system on your device. Please contact Apple for assistance on upgrading the devices operating system.
Is this turned on by default?
No, by default these restrictions are not applied. Someone would have turned them on.
Why can’t you do this remotely?
Apple does not allow us to do this remotely.