In Colorado, at a restaurant, is an employer allowed to schedule someone for only 2 hours in the middle of the day?

And can one be scheduled to work for 4 hours but be sent home only after 1 and half?

I could not find anything on the DOLs site about hours other than overtime laws.

I ask because I used to live somewhere where the law was 4 hours, meaning if you were scheduled at all on any day, it couldn't be for less than 4 hours, and you were to be paid for a minimum of 4 hours if a manager asks you to leave early, unless you asked to go home early.

Yes, everything in your post is legal.

There are less than a handful of states that have "reporting time pay" laws but Colorado isn't one of them.

That's the second time in two days I've heard about this mythical place where shifts cannot be scheduled for less than 4 hours. There is no such requirement. There are places where if you are sent home after working less than your scheduled shift you must be paid "reporting time pay" of up to four hours, but nowhere does the law require an employer to schedule you for no less than four hours.