https://www.payetteforward.com/cant-delete-apps-iphone-fix/
"Open Settings and tap Screen Time -> Content & Privacy Restrictions.
tap content and privacy restrictions in screen time
Next, tap iTunes & App Store Purchases -> Deleting Apps. Make sure that Allow is selected. When Don’t Allow is selected, you won’t be able to uninstall apps on your iPhone.
If you received your iPhone through work or school, there may be a preinstalled profile that’s preventing you from deleting apps. To check if this is the case, open Settings and tap General -> VPN & Device Management.
Here you can see a list of the Configuration Profiles installed on your iPhone. If you’re allowed to (ask your boss or school first!), you can tap on the Profile, then tap Remove Profile."