Well, since you wanted to remove the cursor, I figured you didn't care whether the player was able to select units.
I just assumed It's quite hards to give orders when you don't know what you're pointing at.
May I know what you're trying to do?
The only way I know to let the cursor (dis)appear in-game is to disable the user control.
Another method to permanently remove the cursor (cannot reappear in-game) is to import a custom one that doesn't show anything.
Depending on what you want, perhaps there are other solutions.