Mozilla Firefox,
1. At the top of the Firefox window, click on the Firefox buttonOn the menu bar, click on the Tools menuAt the top of the Firefox window, click on the Tools menu, and then click Add-ons.
2. In the Add-ons Manager tab, select the Extensions or Appearance panel.
3. Select the add-on you wish to remove.
4. Click the Remove button.

Google Chrome:
1. Click the menu icon "≡" at the top right of the browser window, choose "Tools" and choose "Extensions" to open a new "Options" tab.
2. click "Remove" to delete it completely.