Just click the X as you see on the picture and all vertext color will be gone!!!

http://img84.imageshack.us/img84/5181/vertexcolor.jpg
EDIT: Should have looked at your screeny first, lol!!!

Well, looks rather like a failure of the mesh. In edit mode recalculate normals outside "CTRL+N", remove doubles "W, remove doubles" and/ or merge verts, if you find lose ones "W, merge"...
TheDaywalker :rock: