Their own site says to use Control panel: http://www.reimageplus.com/uninstall/
Worth a try. Post back if it doesn't work.
Why did you agree to it being installed when you installed something else?
All of a sudden every time I try to navigate through a site an ad for reimageplus on a separate page or tab... Can you help?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic