To filter your menus, go to Menu Filter in the Add-on Manager and click on the options button, or click on Menu Filter in the Tools menu. Note that this add-on can't move menu items around. There are no plans to add that functionality, so please don't ask for it!
![Menu Filter – Firefox 向けアドオン](https://cdn-ak-scissors.b.st-hatena.com/image/square/19fb79a4e0b4539e471781ff1f3fe69f6ceef1be/height=288;version=1;width=512/https%3A%2F%2Faddons.cdn.mozilla.net%2Fmedia%2F%2Fimg%2Fzamboni%2Fanon_user.png)