Sorry for delay,
Now I see, the problem occurs only when you try to add image.
I suggest to use other editor than "old" TinyMce like: JCE or JCK Editor, this solution will be easy for users, they'll use only one [image] button from toolbar
See all features of those editors, they are great for front-end/back-end - users - you can choose which icon you want to see. Then disable [image button] from Plugins Manager to hide them.