Assuming it is the toolbar from Ask.com:

http://dl.ask.com/toolbar/moz/faq.html#na3

Quote:
How do I uninstall the Ask Toolbar?

You can easily uninstall the Ask Toolbar using the instructions below:

Firefox 1.5

1. From the "Tools" menu choose "Extensions".
2. A list with all your installed Firefox extensions will pop up. Find "Ask Toolbar", click on it.
3. In the bottom left corner of the list window click "Uninstall".
4. Restart Firefox.


Firefox 2.0

1. From the "Tools" menu choose "Add-ons".
2. A list with all your installed Firefox extensions will pop up. Find "Ask Toolbar", click on it.
3. Three buttons will appear underneath the "Ask Toolbar" listing. Click "Uninstall".
4. Restart Firefox.
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Bitt Faulk