A MAC address gets deleted automatically if the switch does not receive a frame from this address within a reasonable time (default is 3 to 5 minutes usually). If you want do delete it by hand you can do so by using the admin interface, the function is called "ARP Address table management" or similar, depending on your model of switch.
Some devices allow you to limit the number of MAC addresses on any port, or even restrict access on specific ports to a fixed MAC address.
