If I no longer own the car, am I still obligated to pay the SR22 insurance?

An SR22 is proof of Financial Responsibility that is filed with the state DMV.  IT was probably ordered pursuant to some infraction on your behalf or a bad driving record; or because you were convicted of something that involved operating a motor vehicle.  Each state differs on how long you are required to have the insurance (I think Illinois is 3 years but you need to double check that).  Your requirement may be tied to your sentencing so I would not cancel it just yet.  If you are permitted to cancel it and fail to file the appropriate form with the DMV, an SR-26 is filed by the insurance company and your license may be suspended.  Now, there are SR-22's to cover you should you drive an uninsured vehicle.  But I think it may be best for you to contact the DMV and the Secretary of State, who monitors them there.  Good luck.