You can revert search to default as follows:
1. Open Firefox.
2. Type "about:config" to address bar.
3. Search for keyword.URL value, rightclick on it, and reset it to default.
You can also manage search engines as described in this Mozilla support article.
have used 2011 remove tool, its finally gone away!!!
- how do i now remove AVG secure search in firefox navigation bar and revert to google