I used to do the same thing when I just started out using MQ.
I ended up getting so frustrated that I couldn't /unload pluginname that I would unload and exit MQ, alter the MQ.ini to make the plugin not be on the list for autostart, then just start MQ up again. I didn't find out what I was doing wrong until I mentioned the frustration to a friend of mine.
Some questions you just have to ask, whether you feel they're stupid or not. I would have saved myself a lot of annoyance if I had.