i cant turn off passcode lock

You also have to delete the provisioning profile that added the requirement for passcode lock. Settings/General/Profile.

Although it is rather foolish to not have a passcode on an iPhone, unless you have no personal information on it, no apps that access any sites that have anything to do with money, and no contacts on it. Without a passcode you are open to identity theft when your phone is lost, stolen, or just left around your office unattended.

Have an Exchange account on your phone? If so, the ability to disable the passcode can be disabled by a profile also installed on your phone.

You go to settings, Touch ID and passcode (if you have a touch ID enabled device, if not then it will be just passcode) and then once it’s ask you for the password and then you get in you click turn passcode off and then type in your passcode and then your set. Warning!, it will turn off the Touch ID too.

I've deleted my Exchange account, and I still can't turn off passcode lock. Any ideas ?

How do I turn the passcode option off on my phone? I don’t want to use it.

Do you mean the passcode lock for your device?

Try Here...

https://discussions.apple.com/thread/2417742

Are you accessing an Exchange account on your iPhone that is provided by your employer?

Contact your employer to remove this setting with a profile that have installed on the iPhone.