Allied Telesis AT-FS970M Series - Manual (Page 900)

Chapter 58: Port-based and Tagged VLANs
900
Deleting VLANs
To delete VLANs from the switch, use the NO VLAN command in the
VLAN Configuration mode. You cannot delete the Default_VLAN. The
untagged ports of deleted VLANs are automatically returned back to the
Default_VLAN. Here is the format of the command:
no vlan vid
This example deletes the VLAN with the VID 12:
awplus> enable
awplus# configure terminal
awplus(config)# vlan database
awplus(config-vlan)# no vlan 12