I suspect you will not find this easy to do, if at all possible.
From: How to reset your AirTag - Apple Support
"An AirTag can be associated with one Apple ID. If you want to use an AirTag that someone else has used, they need to remove the AirTag from their Apple ID first as described in this support article —> If an item or device is connected to another Apple ID - Apple Support .
In similar situations where a device is blocked by an ID that cannot be removed, Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Do this online at: Activation Lock support request - https://al-support.apple.com/#/additional-support Apple says, "Proof of ownership documentation is required," but does not detail what currently constitutes proof. Prior to this new online service Apple typically required the original receipt issued by Apple or an Apple Authorized Reseller and documented provenance (so typically it would be the original owner who does this, or a descendant with legal proof of ownership). This will give you access to the device but won't restore access to the account used to lock it. There is nothing that can be done to expedite an Activation Lock request.
Apple recommends you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support
However, I have not read about that service in the context of Airtags. If you find that they do offer it then please report back here so we learn something new.