Whether you just bought a brand new or a previously owned home, you cannot be certain who is carrying around a key to your front door. Rekeying the locks yourself is very inexpensive compared to what it would cost to have a locksmith rekey your locks. To rekey a Schlage lock, all you need is a Schlage rekeying kit and the key to the current lock. Schlage locks can easily be rekeyed to match any Schlage lock in your house so one key will open all your locks.
Insert the current key into the lock and turn it 90 degrees clockwise to a 3 o'clock position. Locate the catch (small metal button on the left side) on the door knob stem and use the front tab on the key gauge (included with the rekeying kit) to push in the catch to release the knob. Pull the knob off.
Turn the key 90 degrees (counterclockwise, to a 12 o'clock position) and pull the key out. Release the cylinder to let the tail end of the cylinder drop inside the knob. The keyway (where you insert the key), looking from the front, should be lower and on an angle. Push the cylinder through and out of the back of the knob. The cylinder cap will depress as you push to fit it through the knob.
Push the C clip (retaining clip) off the end of the cylinder using the U shape on the key gauge. Insert the new key and turn it 90 degrees clockwise. Use the plug follower (plastic rod from the rekeying kit) inserted in the rear of the cylinder to push the keyway and key out the front. Do not remove the plug follower from inside the cylinder housing. The plug follower will hold the bottom pins and springs in place.
Working over a table, turn the plug (part with the key) over to dump out the bottom pins. Insert new bottom pins into the plug. The new pins must be flush with the plug. If a pin is not flush, remove it and try a different pin that will sit flush. Reinsert the plug into the cylinder housing while forcing the plug follower out the back. Insert the C clip on the cylinder. Remove the key.
Depress the cap on top of the cylinder with your finger so it will easily fit back into the knob. Line up the cap with the slot inside the knob sleeve. Push the cylinder into the knob. Insert the new key and turn it 90 degrees. Align the catch button with the slot on the shank and use the key gauge to press in the catch button. Slide the knob onto the shank. Rotate the key 90 degrees counterclockwise (to a 12 o'clock position) and remove the key.