I bought a used MacAir and its locked in "Activation lock", is there any way to get rid of the old Apple ID?

Click on this link to read about 'Activation Lock for Mac' --> https://support.apple.com/HT208987

Activation Lock is a security feature that's designed to prevent anyone else from using a device, if it's ever lost or stolen. To learn more click here --> http://support.apple.com/HT201365

For an individual to remove an activation lock absolutely requires the information for the account that applied the lock. Click on this link to learn 'How to remove Activation Lock' --> https://support.apple.com/HT201441

If you do not know the required information and you are not the original owner, get the owner of the account to remove the lock or return the device for a refund or recycle the device. The device is otherwise useless to you. If the owner is unknown and has not provided contact information as a message showing in the login screen, there is no way to contact the owner unless the person who gave you the device knows them.

Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Your problem may being able to provide this proof. 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 state 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 is a relatively new feature on Macs but I presume it is similar to Activation Lock on mobile devices.