Unable to fully delete app on iPad

Which app is it exactly?

If it's one of Apple's default apps, it may not be deletable.

If it's a 3rd party app downloaded from the App Store, then you may have deleting apps disabled in Screen Time settings.

You have provided no information as to your iPad model or the installed version of iOS/iPadOS - this information being potentially significant as to the inability to delete specific Apps from your iPad.

Start here:

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

Assuming that your iPad is not centrally managed by an Educational Establishment or Business (as the device may be remotely managed) - if you are experiencing difficulties with adding, updating or removing Apps from your iPad, you’ll need to check your ScreenTime restrictions:

• Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Adding Apps - set to Allow
• Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > Deleting Apps - set to Allow
• Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases > In-app Purchases - set to Allow