two sccm to one tenant intune

I have a number of devices configured in SCCM "A" co-management with an intune tennant "A"
I have a number of devices configured in SCCM "B" co-management with an intune "B" tennant.
Now I need to undo the SCCM comanagement "A" and make a new co-management the intune tenant "B"

What are the risks and process to do this?