Can this ring be completely removed if the steerer and spacers are adjusted accordingly or does this serve some purpose?
EDIT - removing old answer bc question changed.
That conical spacer presses against the upper bearing assembly. If you take it out you'll need some way to pre-load the bearings. Unless you can find another part to replace the function of the conical spacer you cannot remove it.
Why do you want to remove it? Are you trying to slam your stem?
Here is an article about an appropriately named product that might get you where you want to go: Slam that Stem.
The tapered spacer is usually for water proofing the headset (dust cover), you can remove it as long as there is enough pre-load tension when assemble back the stem.
It is actually quiet useful to keep all the dirt and water away, especially if you leave the bike outside the rain. There usually is a set of O-ring(s) inside to keep the water dripping down the steerer tube.