How do I adjust a Delta bathroom faucet that has a scald guard?
This is a feature of the faucet called "scald guard" that you can set to prevent overly hot water from burning people. I have a new construction and I found that the default setting was a bit overkill, so I adjusted it.

You only need a small hex key (size?) to adjust the scald guard. Before you begin make sure you close the bathtub drain or put something over the shower drain, the screw is very small!

There's a tiny screw at the bottom of the faucet:



Unscrew this and then remove the handle, you should see the plastic assembly. Take note of the circular piece, you need to slide this off in order to adjust the faucet:





Now you're ready to adjust it. Note the triangular plastic bit that is at the "4 oclock" position. As noted on the plastic part itself, turning it counter clockwise let's the handle turn more towards hot, and clockwise turns it colder. The circle thing is in there with saw teeth, so you just can't turn it, you need to pull it out, turn it, and then push it back in. I moved mine to be closer to the "2 oclock" position:



Now you can slip the circular plastic piece back on, then the handle, and then the small hex screw again to finish it off (basically go in reverse order). Your faucet should now be able to turn to the hotter position. 

Adjust to your liking; also be cognizant of safety, the thing is there for a reason, and the plastic bit will prevent you from adjusting it too far towards hot. My personal set up is a little bit hotter for our master shower and bath, but not as much in our guest bathroom since there might be kids, etc.