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

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.