closure of GST number -reg

all the returns up-to-date must be filed and there is no liability to pay , if any. 

and cancellation of gst registration executes with filing of GSTR_10 (final return) after paying all taxes , if dues . 

thanks !!

after filing the return status shown as GSTIN cancelled 

you can file gstr_10 from the GST PORTAL after login under the section returns >> final return 

after filing the return , the status will be filed and even after the cancellation you will be enable to login so do not worry now after the cancellation there is no liability to filed any returns .