How to remove adhesive tape badly stuck to the glass?

I have recently bought a house. The previous owner has stuck mate adhesive tapes to cover all windows from half length to the bottom. I have spent half a day removing just one side of the window and it was not successful. I have used sharp objects to scratch the tape off. I have used this spray material called “Goof Off” which supposed to be an adhesive remover. But it makes it harder by smoothening the edges stuck to the window. How can I easily remove the adhesive tape from my glass windows? Is there a special technique to do it?