Pre COVID I had a training team using iPads purchased outright, not linked to anyone just a resource. Now that I’m ready to reissue to new trainers, I’ve noticed 6 of the iPads 0000 codes have been changed. the last team in 2019 is no longer with u

Hi Kantlooz, thank you for posting in Apple Support Communities.

It can be a time-consuming process to restore the iPads when the Passcodes have changed and it may require connecting the iPads to a Mac or Computer especially when the iPad becomes disabled. Nevertheless, This Apple link will explain how you can resolve the issue.

https://support.apple.com/en-au/HT211078

You will also note when opening the link that you can contact Apple should the issue continue.

You can do this as follows:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above but also again as follows Apple – Location Selector; or
• Using the "Apple Support" app, available and downloadable from App Store.

Contact everyone who used the iPads?