Go to settings -> Security -> Screen Lock
Issue:
You want to change the screen lock options to swipe or pattern. All options (i.e. Swipe, motion, face unlock, pattern etc) are disabled.
Resolution:
Scroll further down the security settings to Device Administration. Select Device Administrators . If you have anything listed here, you can click on them and see what you have granted. It’s most likely an app that has admin access, typically the standard Email App from Samsung. Deactivate and go back to your lock screen options again.
David J Steele 
Did not help any more tips
I had this problem, and it was a security certificate required to get on my University’s WiFi. When I deleted the security certificate, the problem was fixed. Just scroll down to the very bottom of the screen below Device Administration
Thanks Erin,,
I also had to delete all my certificates. Some people reported having to remove all programs under the Administrators setting or delete their VPN connection. Neither of those helped me – it seemd to be the certificates.
thanks everyone its certificates problem when i deleted all my problem fix
Thanks. Removing certificates worked for me also.
Nothing is working for me. Did all of the above. PLEASE HELP!
I am also having the same problem,nothing worked for mr