How to delete an iPad update

This will only be seen for an update that has been downloaded - but not yet installed. A downloaded (but not installed) update package can be deleted from the location that you describe. Once successfully installed, this package should automatically delete from the device.

As described, something isn’t right. If your iPad has been successfully updated to iPadOS 16.3.1, try a forced-restart - and then look again for the update package.

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

Rolling-back to an earlier version of iOS/iPadOS is not possible.

All System Updates are digitally signed by Apple - and can only be installed whilst the digital signatures remain valid. After release of a new iOS/iPadOS version, the immediately preceding version continues to be digitally signed by Apple - however, usually within a few days, Apple will revoke the digital certificate with which the earlier version is signed.

If Apps no longer work properly following update to a more recent version of the OS, you’ll need to seek assistance from the related App Developer - as only they can resolve issues with their App.

How to contact an app developer - Apple Support

Perhaps consider that iOS/iPadOS updates include both functional and essential security updates. Restoring an earlier version of the OS would undermine the security of your device and your personal data. 

For information, Apple do invite submission of comments via its Product Feedback portal. For iPad and iPadOS:

Feedback - iPad - Apple

Perhaps you have a beta profile installed? Ensure this has been removed from your iPad - as, otherwise, installation of production software updates may be inhibited.

This support page provides the necessary information to remove the beta from your iPad:

How to uninstall iOS beta software - Apple Support

Where do you see this “delete” button?