Start by disabling Find My iPad:
Settings > [Your Name / AppleID] > Find My > Find My iPad - set to OFF
Next, sign-out from your AppleID:
Settings > [Your Name / AppleID] > Sign Out
You’ll have opportunity to save a local copy of your data; if you do so, this data will eventually be merged with the new users AppleID account. If you are happy to have your personal, private and sensitive data (including Keychain) copied to somebody else’s account, you can save a local copy of all your data - otherwise decline. You have been forewarned of the consequences; once merged with another account, other than manually deleting data entries, you cannot reverse the merge.
After signing-out, a forced restart is recommended:
- On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
- On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.
After restart, you wife can sign-in with her own AppleID. Data previously saved during sign-out will be merged with your Wife’s AppleID account.