How to turn off manual focus on nikon d60?

I try to change it in the menu section, but it tells me this option is not available with the current settings.

Whenever I have a question/problem such as yours, I read the user's guide
(aka "the manual").
It is amazing just how much I always learn from that.

If that doesn't help (or if I'm interested in a product I don't own), I check the manufacturer's website.
They have descriptions and specs for their gadgets, often have user forums, and the decent manufacturers all let you download the manuals in electronic form (so losing the book is no longer a problem).

99% of the time that does the trick.

Turn OFF manual focus?

Most new lenses have MA/M switch which you use to do that.

Look on page 57 of your user manual.