How can I reset the computer on this Sububran?

Yes the computer should have a scan tool plugged into the diagnostic socket under the dash to reset the Check Engine light after you have replaced the component that is responsible for triggering the check engine light in the first place but the computer in your car will test and monitor the performance of the "new" sensor and when drive conditions are met it will determine the sensor performance is OK and will turn off the light all though this could take some time (two to three weeks depending on your driving conditions).