Can you delete an update that did not install properly

It depends on what "not properly" means.

If it didn't complete the update process, then Katana-San provided the correct suggestion.

If the update process went to the end but you're experiencing problems, please describe them.

Or, to reinstall a fresh copy of iOS/iPadOS, create a full backup of your iPhone/iPad (1), then restore it to factory settings (you need a computer to perform this step) and, in the end, set it up as new (2).

When done, restore data from your previously made backup (3).

Follow the instructions provided in these support articles:

(1) How to back up your iPhone, iPad, and iPod touch – Apple Support

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

(3) Restore your iPhone, iPad, or iPod touch from a backup

If the issue still persists, contact Apple Support directly using this link:--> Get Support or, even better, make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> Apple – Location Selector. After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

Hello ~ Yes and take a look here:

*If your iPhone, iPad, or iPod touch won't update - Apple Support

*Remove and download the update again

~Katana-San~