Conversion of firm

GST compliance:- you have to cancel the firm's GST registration and apply for new one on individual's name.

if any credit lies in the electronic credit ledger you can transfer the same to proprietor by filing ITC-02. before transferring credit to proprietor make sure all the credit available on the firm's name claimed by firm.

before transferring to proprietor make sure he must be registered under GST.

Income tax:
You have to surrender the PAN on the name of dissolved firm.

Capital gain shall be chargeable to tax in the hands of firm on distribution of capital asset on dissolution of firm.

In my view, dissolve the partnership firm, and open a new propritorship firm with the same firm name. 

Surrender PAN of partnership firm

Surrender gst of earlier firm and claim GST refund. 

Ramaraju has explained very well in detail.

Lot of thanks