My screen lock is set to "PIN", and I can't change it to "Swipe". Why not? I have tried to do the fix as suggested on here however my swipe option states it was disabled by administrator or something like that. Not sure how I even set a PIN in the first place. How do I change this?
Check if you have added VPN connections.

Usually VPN connection requires minimum Pattern/PIN/Password active, and while you have VPN connection created you can't disable it.

To check does you have it, and to delete it go to Settings -> More under Wireless &amp; Networks-> VPN. Keep in mind, this can be different on other Android version, you can search Google for your device.

If there is present connection, after removing them you should be able to change Lock screen settings.