GST registration cancel

Yes of assessee does not file return for 6 consecutive months (3 periods in case of composition) then GST registration is cancelled

Yes agree with Mr Hitesh
As per section 29 CGST Act

b] a person paying tax under Section 10 has not furnished returns for three consecutive tax periods; or

[c] any registered person, other than a person specified in clause [b], has not furnished returns for a continuous period of six months

But As per Section 46 CGST Act , the notice is issued in form 3a to taxpayer who is defaulter of Return filing.
Hence if you got such notice you are liable to file return till date of Notice (even though nil return) else your Registration will not get cancelled