Why can’t I delete apps from the library?

review this

How to delete apps on your iPhone, iPad, and iPod touch - Apple Support

you can delete from the App Library by locating the app and tap/hold, select Delete App

or you can go to Settings > General > iPhone Storage > [app name] > Delete

If you still are unable to delete, check:

Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps

make sure that's set to 'Allow'