How do you delete an app that won't uninstall on an 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

Check to see if Screen Time under settings has Content and Privacy Restrictions on. Under the iTunes and App Store Purchases option choose deleting apps and make sure it is on Allow.