How to fix sticky wheel that s near the shutter button on Canon 6D?

You need to take the top off of the camera body to get to the wheel. A youtube search should show you how, but just be aware that taking it off could void your warranty. If it is under warranty, take or send it to a Canon authorized repair center.

Try opening the camera body and giving a check theres nothing below the wheel that is causing the jarring. But do this only if you have some sort of professional experience. Tutorials look simple enough, but a small mistake could violate your warranty clause. So, the best thing to do is to just go the nearest Canon authorized service center and get it fixed.

Do the settings jump out of order when you turn the wheel? Dirty contacts. It's an easy clean however accessing that part would mean you'll have to almost disassemble the whole camera. Bring it in for servicing. Lesser headaches and heartaches.

That depends on what’s “sticky”. If you got a fluid, eg soda, there you may be able to use something like IPA in small quantities to dissolve the problem. Just have the camera inverted so stuff doesn’t go further into the camera.

If something is worn it will need replacing.

Otherwise, camera repair shop.