The mfgr's name is on one or more pieces (face of bolt) call mfgr and ask how to remove handle. Like you I would think loosening the screw would alow it to slide off.

Start by working the latch mechanism, then loosen the cover plate in a counterclockwise fashion with your hand or wrench.

The cover plate doesn’t come up because of the lever…..if I pry up the cover plate until it hits the lever and turn it I don’t see a catch or area to pop. Not sure you can see the lever and how it keeps the cover plate from coming up. I tried Kwikset 800 number and that was frustrating, I got someone who doesn’t believe what I’m describing, I guess they don’t have knowledge of really old locks. I will try them again later and hope for someone else. I’ve watched 5 videos and none match up.

Ok I finally found the right video while on hold with Kwikset, turn the hex screw til it stops and just lift handle up and off and then the cover plate comes off. I can put the axe away now.

Positive.... share the video link.... this can be helpful to others ... thanks