Wrong GSTIN in GSTR-1

You can not change GST No. however you have to do 2 things, First ask your purchaser to add that invoice in GSTR - 2 and then you have to accept the same in GSTR - 1A. and the second thing, you have to ask the party, GSTN no of whose mentioned while filing GSTR - 1, to reject the invoice.

But as we know presently GSTR 2 is suspended so you can just wait and watch.