FAQ - Geek-in-Training/Firefox-Addon-Bar--Restored GitHub Wiki
Can I Hide the X Button?
Yes, it can be moved or removed the same way as any other icon. Either right-click on it and select Remove from Toolbar or else enter Customize Mode and drag-and-drop it where-ever you would like. (See the Firefox support page for more information on customizing Firefox.)
I Have a Problem, How Should I Contact You?
You could either send me an email or see the issue page here.