To change entry knob cylinders, simply insert the master/control key and rotate it 1/4th turn counterclockwise to the 9:00 o'clock position...
...and pull gently. The cylinder will follow the key out of the knob.
Then, simply insert the master/control key into the new cylinder and rotate the key 1/4th turn counterclockwise. Slide the new cylinder into the knob and turn the master/control key 1/4th turn clockwise to the 12:00 o'clock position and remove the master/control key.
The cylinder change is now complete! After practice, typical time to perform this task is less than 5 seconds.