It does not need to remove any metal. Since the steel's only function is to re-align, the sharpening steel can be perfectly smooth and still do its job. You'll see many bumpy steels on the market, but this is almost certainly because consumers think that steels must have bumps to work. The bumps can actually mess up the edge, and make the work of steeling more difficult. There are two schools of thought on steels.
Some people use grooved steels, which align the edge more aggressively but are harder on the edge.
I use a smooth steel, which is easy on the edge but may align the edge more slowly. Then switch to the other side and do it again. Repeat a number of times until your edge feels sharp and nice again. I hold the steel in my left hand, the blade in my right, and lightly run the blade along the steel while keeping the steel stationary, but it's perfectly fine to move both steel and knife past each other at the same time, or whatever works for you. Most people run the knife down the steel edge first, the same direction you use when sharpening.