If you are running MSTP, you might have explicitly created some spanning
tree instances. If so, you can delete any spanning tree instance except instance 0.
You can also remove VLAN members from an instance. When you remove a VLAN
from an instance, the VLAN automatically becomes a member of instance 0. (By default, instance 0
includes any VLAN that is not a member of another instance.)
If you remove all members from an instance, the BIG-IP system automatically deletes the instance.
If you are
running RSTP or STP, you cannot delete instance 0 or remove members from it.