There is no process to change a Community Interest Company (CIC) into a SCIO, you will need to set up and register a new SCIO with OSCR, transfer all property and assets to the new SCIO and then close the CIC down.
Make sure you check your articles of association for the CIC first to see what restrictions there are about the transfer of assets – a CIC usually has an asset lock in their articles of association which restricts where any assets can be transferred to.