Need installing a roller
I'm sorry to say I don't know what it is you need. This is not the proper way to access the roller. Taking the door down is a mandatory step, and not one you can get around. It's the only way to access the rollers for removal.
If you are unable to remove the door through normal means, then you may need to contact a professional to come out and do it for you. Note that some doors need to be taken down from the inside, which can be troublesome.
You will definitely need the help of a professional then. If you cannot remove the door, then it won't be possible to replace the rollers by any means. There is no other way; it has to be done. Removing the side frame won't allow you to properly remove the original or install a new one.