Yup, they're pop-rivets.
Also called "blind" rivets, they're used when you can't get to the back side to buck a conventional rivet. Here's a Web site with lots of info:
http://www.emhart.com/products/pop.html
There's a neat video that shows how they're "popped" in place -- click on "How they work". To remove them, you drill out the head and use a punch to drive out the body of the rivet. Like any rivet, the backside is bulged out (that's what holds things together) and it's impossible to pull the rivet out through the front of the work unless you're willing to drill a huge hole.
Once you see how they're placed, the removal process is pretty obvious. If you're careful, you won't enlarge the hole in the workpiece, so you can replace the rivet if you need to re-fasten something in the same place. The downside is that the "dead" body of the rivet falls into whatever space there is behind the work and stays there forever, rattling around.
>>Are there other ways to remove it without a drill?<<
You can use a sharp chisel to remove the head, and then punch out the tail, but it takes a better chiseler than I to not screw up the surface of the workpiece.
Drilling is a snap if you use a sharp drill. The drill should be the same size as the hole in the workpiece, and the punch should be just large enought to fit in the hole in the rivet. Some people like to use a large drill and magically stop just as the drill is about to contact the workpiece. It's easier than it sounds.