I had to replace my Droid 4 (power button quit working), and one of the setup programs turned on the screen pattern lock.
Drove me CRAZY until I discovered this:
Try hitting Menu -> System settings -> Security & Screen Lock. Near the top of the screen, right underneath "SCREEN SECURITY" it should say:
Screen lock
Pattern
Press it, the screen should now say "Confirm saved pattern" and present the nine dot array. Put in your screen pattern (you may have to do it twice) and the next screen should show all the screen lock options: None, Slide, Face Unlock, Pattern, PIN and Password.
Choose the one you want.