how to delete iPad update
How do I delete a corrupted update
Has the update installed? If so, you'll not be able to roll-back the update - but you can, however, reinstall a fresh copy of the most recent version of iPadOS supported by your iPad by performing a factory restore:
Restore your iPhone, iPad, or iPod to factory settings using a computer - Apple Support
If the corrupted update has not yet installed, you can delete the update package:
Settings > General > iPad Storage >
Scroll down the list of Apps (tap Show All if necessary) until you find the Update - tap, then select Delete Update