Well FWIW I'd ask the employment office for advice on if you have to take the demotion and whether you are eligible to quit. I contested a number of UI claims over the years and a quit always worked to DQ an applicant except when I offered employment other than what he'd been hired for. ALL MO btw
If you get yourself dismissed for cause it will cost you a few weeks DQ so I wouldn't do that ,besides your work record and recommendations would then have a big hole in them. The best way to find a job is to have one,so my advice is to hang onto that one ,keep a good attitude as best you can and keep looking ,give ample notice ,DON'T burn your bridges man, as much as you may want to,you never know when you may need to cross them again.
Don't rule out opening your own store either or partnering with someone in competition with these people, my experience is that big companies give shitty service, the company that bought me out is still renting my building so no one starts operating out of it. When the lease is up if they say they are going to move ,I plan on telling them go ahead but don't quit paying the rent ,cuz some one else will be here to compete with you shortly after you leave,the very last thing they want is a small company start up in a community where the new guy is a known commodity and can give better service.
Are there other stores close