Needs guidance w r t cancellation of gst registration

Needs guidance w r t cancellation of GST Registration of one of my economically weaker client – Case details are as below; 1) Nature of business - Online selling of accessories on Amazon 2) GST Registration GOT - 1-APR-2018 3) Returns Filed till date - GSTR 1 - APR TO JUN 2018 & GSTR 3B – APR 18 4) Returns not filed during - GSTR 1 JUL-18 TO TILL DATE & GSTR 3B MAY-18 TO TILL DATE Note -Up to November 2018, there were few transactions done by client -December, 2018 till APR-2019 No transaction done by client. -May-2019 1 transaction of of below 500/- again done. -Input credit surplus since beginning (Apr-18) -Sale type is B2C 5) Registration Cancellation request done online w e f 1-DEC-2018 Note - Request submitted on 5-JUNE-2019 online to cancel registration effective from 1-DEC-2018 6) Reply from Dept 7th June, 2019 - “Cancellation Details - Others (Please specify) - Please file all due pending GST Returns” 7) While doing compliance of above Dept notice - To file late returns GSTR 1 and GSTR 3B client don’t have any option other than to pay late fee/fine for return Note - Although there is no tax liability – Input credit is always in surplus in records. Registration number is still active, which will further increase liability of late return fine more and more. Kindly guide how to cancel GST registration by avoiding late return fine as per law, because practically there is no tax liability of client and volume of business in every month always max 2000/- As on today total need to pay approx. 30k at least to just cancel registration. Which is practically not fair.