How to cancel a mate operation

I'm just starting to use SW2014, and mating in assemblies needs to be changed somehow. My assembly has hardly any planar surfaces, and I have to fiddle around with the mates. In SW2014 if I cancel a mate operation because it says it won't work, SW puts the mate in anyway, and the feature tree goes red. I don't know how to cancel a mate with the mate being inserted.

SolidworksAssemblies