If you have done not single business then you have to file a nil return monthly or if you want to close the gst then also have to file nil return until you file a final return
You will remain liable to pay tax (including late fee) till you file your returns. You may not be able to run your business with the same GSTIN now and in future also. Government may recover the dues from you in future also.
Filing Returns under GST Regime is mandatory. Even if there is no business transaction in a particular month , you have to file "NIL GST RETURN" for that particular period.
CONSEQUENCE OF NOT FILING GST RETURNS :
The CGST Act 2017 vide Section 29(2) has given powers to the Proper Officer to cancel any person's Registration who have not filed GST Returns for a period of "SIX MONTHS".
Therefore, it's better to file all your pending GST Returns and clear all your GST liabilities ( if any ) and then surrender your GST Registration ( if you are not willing to commence your business now ).
you Please do what ever you want .the choice is come up to you.
GST don't have any option .only Collecting dues from you . That they will do in time . But you don't have any other option only obey the orders of GST and pay off the dues.