VaranisArano wrote: »This is probably a stupid question on my part, but I assume that the normal unequip command is not working?
To unequip, you can right-click on the disguise in the disguise slot and choose unequip.
If that is presumably not working as intended, often disguises will be destroyed if you get into combat with enemies from that quest who are normally fooled by your disguise. So unless the area is quest instanced with the quest finished, you may be able to return, get into combat with the enemy the disguise is designed to fool and lose it from your inventory that way.
For more specific advice, it would help to know the name of the disguise and the quest or quest area its a part of. List: http://en.uesp.net/wiki/Online:Disguises