Regular to Composition

u need not to cancel gst reg


u can simply amend from regular to composition scheme.

by way of amendment in core field section

Dear Hannan Shaik Sir

The window of opting for Composition Scheme [ SECTION 10 ] has been closed now. It will again open in the month of March 2019. So for FY 2018-19, you have to carry on with your Regular Scheme Registration and file all the relevant Returns ( i.e. GSTR 1, GSTR 3B and 1 ANNUAL RETURN GSTR 9) and can opt for Composition Scheme only in the month of March 2019 for FY 2019-20.

definitely u need not to cancel gst registration u can simply amend from regular to composition scheme.

As per sub rule( 3)of Rule 3 CGST Act 
to switch from regular to composit scheme can done prior to the commencement of the financial year 
Hence taxpayer can switch to composite scheme only at the begining of FY