To disable a Firefox Add-On follow the instructions below.
1. Click On Tools.
2. Click On Add-Ons.
3. Select Add-On you wish to disable.
4. Click on the Disable button.

To close all open tabs not including the one selected follow the steps below.

1. Right-click in a empty space in the tab bar
2. Click Close Other Tabs

1. Write it down and come back to it.

2. Wear something to remind e.g. a piece of string around your wrist.

3. Tell someone else to remind you. They may not remind you but telling someone will help you remember.