The only place i know is if you go to plugins and scoll down to the forum plugin and click settings you can disable attachments and also set the size. The blog does not have that option in the plugin settings for blog.
If the privacy and permissions under photo (upload photo - remove the check mark) does not do anything with the mini menu, then from my understanding it will take a code mod for the mini menu and it will be either on or off for everyone regardless of role (we can however allow a moderator or admin exception). If you want to hide that that menu let us know and i will try to assist you with that mod..
Now let me see what i can do to mod that minimenu image so they cant use that either.. and ill be back with you..
I commented out the creation of that element in ow/static/plugins/base/js/htmlarea.js file and it still showed.
Then i changed the css to display:none in ow_static/plugins/base/css/htmlarea.css a.image and it still showed.
im slowly running out of options here lol
There used to be an array in 1.53 init php in the forum plugin but now they redid it for 1.6 and i cannot even find that var anymore. Sorry i admit defeat, its too much for my skill level sorry i cant spend any more time on this for right now.. :)