My motion sensor was tripped. Is there any way to reset the sensor so it is "cleared" and ready to detect further movement?
No. Motion Sensors have a built-in function called "dwell time." Dwell time means that after a motion sensor is tripped it will need a three-minute period in which it detects no motion in order to "reset" back to its default detection mode. This prevents the sensor from sending out multiple alerts for the same motion.
To reset the sensor, clear the detection area of anything that might create motion (such as you, your kids, or your pets) for a full three minutes.