can i lower the rear one inch without lowering the front ? if so would it cause any problems. or is it a bad idea ?

You can physically do it. but why? It will affect your front end alignment such as caster, camber, etc. This may have a detrimental effect on how the car steers and handles. You could have it re-aligned but you would have to come up with the new specs. It will also have some affect on CG although I don't know if it will be negative.