Allied Telesis AT-S63 - Manual (Page 528)

Chapter 30: Protected Ports VLAN Commands
528 Section VI: Virtual LANs
Examples
The following command uses Syntax 1 to delete untagged port 12 from the
InternetGroups VLAN:
delete vlan=InternetGroups port=12 frame=untagged
The following command accomplishes the same thing using Syntax 2:
delete vlan=InternetGroups untaggedports=12