How to remove non-retina support/images?

I am going back to an old half-done project which has support for pre-retina devices. I want to get rid of this support for pre-iPhone 4 devices and just use my retina-ready “@2x” images, but I am not clear how to start. Everything I try results in errors.

Is it mainly in the config? Basically I want to delete all the non “@2x” images – cut down on the file size and remove all the non-retina worries.

Thanks in advance for your help.