I use Grindz and like and recommend the product. But you can also use minute rice or rolled oats. It must be parboiled rice as regular rice can damage the burrs.

Also disassembling and cleaning with a stiff brush works well. Really using a brush/vacuum is the best way then you don’t need to use coffee to clean your cleaner out. Never use compressed air cans, they often contain a bitterant to prevent abuse and the taste transfers to the coffee.

I’ve had several burr grinders over the years - conical and flat - and the best thing I can recommend is disassembly followed by a stiff (non-metal) brush.

I’ve tried literal soap an water (on my early grinders before I knew better), but honestly just a brush is the best thing I’ve found. I have also in a pinch used a super small flat head screwdriver (think for delicate electronics) to scrape out coffee impacted at the Burr’s screws.

Keep in mind that burr grinders have imperfections - and the ground coffee can “fill in” those imperfections to give a more consistent grind. Unless you are experiencing rancid or other off flavors, I’d just let things be.

If you can take them apart, a wooden skewer is helpful for cleaning off the burrs without damaging them.