Any way to disable camera autofocus?

You sure can disable it. Ignore the first post.

Tap the object you want to focus, but hold your finger on the screen for a few seconds, when the square starts to pulse, release your finger. The square will be gone & AE/AF lock will appear at the bottom.

No way to disable it persay, but you can control it.

Press and hold on the screen where you want the camera to focus and after 2-3 seconds it will focus and adjust itself to the spot you were pressing.

Hope this helps!