Use the point of a spudger to push on alternating sides of the CMOS connector to "walk" it out of its socket.

It may take a lot of alternating before the connector comes out. Be patient, and don't pull on the cables.

To reconnect the cable, align the connector and use a spudger or clean fingernail to push it fully into the socket.

Don't push on the cables themselves, or you may damage the connector.

Pull out the CMOS battery cable by the tab using tweezers.

Remove the CMOS battery.