My patio door sliding wheels are worn, how do I get them off to replace the?

My patio door has become very stiff to slide. I took the door off and noticed that the wheels that run on the track are badly worn, so much so that the door runs on the track, not on the wheel. I have tried to adjust but becasue of the wear there is not enough adjustment left.How do you get the wheel asembly off the door frame ? It looks like you may need to remove the glass to get access to securing bolts