Canonet QL19 stuck on Bulb mode: how do I switch it back?

I'm not sure about this "safety catch" button. There's nothing in the manual that leads me to believe that something like that exists (http://www.cameramanuals.org/canon_pdf/canon_canonet_ql19e.pdf) Manual linked from Mike Butkus, who does awesome work in assembling these old manuals. Consider throwing the man some money @ https://www.butkus.org/chinon/donation_policy.htm

In general, though, attempt to "clear the slate" and start over. Wind the film advance lever making sure you get a full crank. Then use the shutter release. At this point, you should be able to adjust your shutter speed. With bulb mode, hold down the button and hear the shutter open. Keep it held down. Release a moment later and hear the shutter close. If you don't hear it close, then attempt to push the button again and it should close.

Please point out the button that you call "safety shift" as it's possible the use may have impacted the camera function. (If it's the self timer, and the self timer mechanism is broken...then you wouldn't be able to clear the slate)