To disable ImTranslator extension temporarily:
- Click the menu button and choose Add-ons. The Add-ons Manager tab will open.
- In the Add-ons Manager tab, select the Extensions panel.
- Locate ImTranslator extension.
- Click its Disable button.
- Click Restart now if it pops up. Your tabs will be saved and restored after the restart.
To re-enable the extension, find it in the list of Add-ons and click Enable, then restart Firefox if required.