4.3 Configuring VLANs
4.3.3 Deleting VLANs
Removing a VLAN from a set command-based switch is just as easy as configuring one. To remove a VLAN from the switch, issue the clear vlan vlan_number command, as shown in Figure . In this example, VLAN 2 is being removed from the domain by using the command clear vlan 2 on the set-based switch. It is important to note that you must issue this command on a VTP server switch. You cannot delete VLANs from a VTP client switch. If the switch is configured in transparent mode, you can delete the VLAN. However, the VLAN is removed only from the one Catalyst Switch and is not deleted throughout the management domain. All VLAN creations and deletions are locally significant only on a transparent switch. VTP domains are covered in this section.

When you attempt to delete the VLAN, the switch will warn you that all ports belonging to the VLAN in the management domain will be deactivated. If you have 50 devices as members of the VLAN when you delete it, all 50 stations become isolated because their local switch port becomes disabled. If you recreate the VLAN, the ports will automatically become active again because the switch remembers what VLAN the port belongs to. In other words, if the VLAN exists, the ports become active. If the VLAN does not exist, the ports become inactive. Use caution when deleting VLANs because it could be catastrophic if you accidentally eliminate a VLAN that still has active users on it.

Removing a VLAN from a Cisco IOS command-based switch interface is just like removing a command from a router. In a previous example, we created vlan 2 on FastEthernet 0/3 by using the command Switch(config-if)#switchport access vlan 2. To remove this VLAN from the interface, simply use the "no" form of the command, as shown in Figure .