Gst number deactivation

First of all he has to rectify all defaults ( File return and pay tax along with int @ 18%) then, he can make application to proper officer for revival of registration. If proper of satisfied then he may revived. If u did not then proper office shall be eligible to for BJA as treating unregistered person and further may levy penalty upto to amount of tax evaded.

But its strange that on same PAN he got the new Registration.

As per 23 , you should furnish all your rerurns with interest & late & Submit application for revocation of cancellation of registration, in FORM GST REG-21 But that is to be done within 30 days from the date of Notice issued under form 3A

So you should meet your concerning officer in this regard , to request for revocation of GSTN

Please contact your jurdistionary officer and revoke your car registration.
After that file your returns with late fee and interest.

otherwise the officer will do assessment and may impose huge penalty.( This is only my view)