The idea was the easy to re-program. You can change to another key easily even without returnning of the keys from tenants. You have to re-key for a new tenant anyway, don't you?
You can chose schlage, which makes your life more difficult.
Yes, it is easy to re-key, but that doesn't mean it is legal to do that. Most of the actions in the states work that way, don't they?
If you are asking how to do re-key without a working key? Search for a $30 reset cylinder
http://www.buy.com/prod/kwikset-83260-001-smartkey-reset-cradle/227882846.html?listingId=220616847
