You can open the about:config page via the location bar and do a search for iMesh via the Filter at the top of the about:config page.
You can reset all iMesh related prefs via the right-click context menu to their default values.

To open the about:config page, type about:config in the location (address) bar and press the "Enter" key, just like you type the url of a website to open a website.
If you see a warning then you can confirm that you want to access that page.

• Use the Filter bar at to top of the about:config page to locate a preference more easily.
• Preferences that have been modified show as bold(user set).
• Preferences can be reset to the default or changed via the right-click context menu.

I changed everything back to default like you said, but everytime I open a new tab it still comes up with the iMesh search engine. I just want this off my computer. What do I now? I've tried almost everything (uninstalled etc.) and it's still there.

EDIT: Never mind, just saw at the bottom of the page it said "disable new tab feature".