Your solicitor should be asked to draw up a title deed passing your title over to your parents. This is then sent to the Land Registry with the appropriate application and they will update the title sheet for the house.
Charges vary, but typically £400-500 plus VAT. You can use AP1. You can't do the transfer unless your parents agree.
My name is ***** ***** I have been a solicitor for more than 30 years
To add to the above.
I am afraid that you will need the agreement of your parents or an Order from the Court to have your name removed from the Title.
I assume that you do not wish to receive any payment - but you will need then to sign the TR1