Use of Hide My Email is entirely optional - and is only available to customers that have an active iCloud+ subscription. Where available, this feature don’t have to be used at all.
Insofar as is possible to disable Hide My Email, you will need to manually delete/deactivate all Hide My Email addresses that you may have created - the process to remove each Hide My Email address being straightforward:
Settings > [Your Name / AppleID] > iCloud > Hide My Email >
For each of your listed Hide My Email addresses - tap, then select Deactivate Email Address
For information about managing, deactivating and deleting Hide My Email addresses, see the iCloud User Guide:
Stop using, reactivate, or delete a Hide My Email address on iCloud.com - Apple Support
For more information relating specifically to iPad, see the iPad User Guide:
Create and manage Hide My Email addresses in Settings on iPad - Apple Support