There should be a small hole on the back of the switch, place a brad all or a pointy tool in the hole and pull out the wire at the same time.

Tom the most important step is to shut off the breaker which controls this dimmer switch. Dimmer switches are sensitive and should never be worked on with out killing the power.

that being said, simply take a tiny flat blade screwdriver which will slide into the hole next to the wire and put some pressure on it. You can then easily remove the wires. good luck

Some switches have a small area where you can insert a pin, or small screw driver that prsees down on the metal holding the wires and releasing them. Others do not have that and the wire must be cut and stripped.

There should be a slot over or under where the wire is pushed in. try taking a toothpick or something of that sorts and insert it into that slot. the wire should then release.