ICX7250 default vlan can't be removed from any ports?

[dm]

I have an ICX7250 , it has default vlan 1, I've added two new vlans 991 and 999, and I can add and tag vlans to ports but I can't remove the default vlan 1 from any of the ports ???

ICX7250-48P Router(config-if-e1000-1/1/48)#vlan-config remove vlan 1
Error - Port 1/1/48 membership removal not applicable for default VLAN id.
Port(s) ethe 1/1/48 can not be removed from VLANs 1

ICX7250-48P Router(config-if-e1000-1/1/1)#vlan-config remove all
Port(s) ethe 1/1/1 can not be removed from VLANs 1

Why not???  I don't want the default vlan to be a member of my trunk ports/uplink ports! Actually, I don't want Vlan 1 at all.

ICX7250-48P Router(config)#no vlan 1
Error - Default VLAN [1] cannot be deleted

SW: Version 08.0.95mT213
UNIT 1: SL 1: ICX7250-48P POE 48-port Management Module