How do I remove these nails? I am removing a wall in my basement that was framed in , and they used a nail?

gun to secure the board to a concrete basement floor. The head of the nails stick up about 1/2" and have an orange plastic type ring around it. Are these hard to remove? I haven't even attempted to take them out yet. Also, do I need to fill the holes after removal, and with what?

I don't think you can cut those nails with a sawzall. They were put in with a 22 Hilti power nail gun. That's why you see the orange ring around them.
The best way to remove them is to knock them back and forth sideways then try to pull them up with a long crowbar. That is, assuming they were driven vertically through the plate, not toe nailed.

Most times the nails are driven into the concrete just enough to keep the plate from shifting while the partition is being erected.

If all else fails, set the depth of a circular saw to 1 1/2" and cut the 2x4 cross-ways next to the nail, knock out the short pieces then hit the nails sideways and snap them off. Then, if any are still sticking a little above the floor, grind them flush.

Sometimes they can be pulled with a crowbar. A four inch grinder with a diamond blade makes short work of them.

If you smack the baseplate, the board next to the floor, and the nails will not come out with a prybar. then cut them with a sawzall. If they do come out and leave a void in the concrete, then fill the void with mortar or hydraulic cement. Good Luck

a concrete nail use a crow-bar

Your better off to cut them off flush with the concrete. If you try and pull them, there's a good chance that you'll bust out a chunk of your floor.
You can use a hacksaw, sawzall or a grinder.
There;s really no need to fill any hole that might be left after cutting