How to adjust credit notes (negative sales) of fy 17-18 in current month gstr-3b if there no sales

Dear Experts,

Note: One of the company had business in last FY 17-18. However, as a result of venturing into a new Partnership there are NO business transactions in current FY (and there will be none), its GST registration will be surrendered by end of this FY.

However, upon Audit, it was noted that certain Credit Notes were not reported in GSTR-1 and 3B of last year (FY 17-18). To adjust the same in current month (Dec-18) GSTR-3B, the total of such credit notes needs to be entered as negative figures in Table 3.1 for Outward Supplies.  BUT GSTR-3B is NOT accepting any negative values.

Then how can this be correctly reported ?  Please Advise.