Hello Ivan!
For PVST(+)/RPVST an instance of STP is running for each VLAN (as the number of VLANs increases, so does the number of independent STP instances).
In these two modes and just like you specified we can disable stp per vlan (no span vlan #)
Unlike PVST(+)/RPVST the whole idea behind MST is the capability to map multiple VLANs to a smaller number of STP instances.
With that being said, MST "deals" with MSTI Instaces and not directly with VLANs.
Each VLAN is mapped with an instance => By default, all VLANs are mapped to the IST (MSTI 0) instance. You can explicitly map them
to other instances, if needed.
That is the reason why I do not think we can disable MST on a vlan basis like pvst/rstp as MST operates with instances.
Hello Sebastian, I think in fact "no instance instance_id [vlan vlan_range] " will return to the default VLAN-to-instance map
For example if vlan 100 is mapped to instance 1, the command no instance 1 vlan 100 will return vlan 100 to his default instance MSTI0 (IST).
(http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/spantree.html#wp1102007)
You can check that with the command show spanning-tree mst before and after.
Example :
##### MST0 vlans mapped: 1-9,11-19,21-29,31-39,41-99,101-199,201-4094
/////
##### MST1 vlans mapped: 10,30,100
Kind regards
Karim
