Blackberry,
That is your basic ZZ cam. You need to have it in the machine for you basic ZZ stitches. I guess they figure you'll use it more than the plastic pattern cams so they made it from steel. It just pops off, that's what the grove in the raised center portion is, finger groves. It might need some fresh oil to encourage it, if it's reluctant to come off it could be all gummed up with old oil.
If you don't have a manual, you do need to get one. Kenmores are great machines but they are not really user intuitive. I've found you need to have a manual to get the control settings exact. Whey they are exact you get great performance.
The manual also tells you about the metal cam and plastic cams and what to do with them.
Joe