Help

As detailed within the support page, helpfully provided by ProustGiulio, you must restore your device - as this will reinstall the production version of iPadOS.

Beta Removal

https://beta.apple.com/sp/betaprogram/unenroll#ipados

How to uninstall iOS beta software - Apple Support

Restore

Restore your iPhone, iPad or iPod to factory settings – Apple Support

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Follow these instructions:--> How to uninstall iOS beta software – Apple Support

Regards

Giulio

You wait for the next iOS official update, or, if you have a backup created before installing beta software, see section "Remove the developer beta by restoring your device", in the support article I posted in my first reply.

Regards

Giulio