Is there a way... once you've clicked the icon to view take lanes... and once you've comped or bounced takes/edits/clips to a single file...
 
...is there a way once you have that single file... to then keep the file in the track, but remove ALL take lanes... so that there is not any... and the Take Lane icon stops glowing blue, and goes back to being just a normal, single track again.
 
I find that no matter what I do, once I've even just clicked the Take Lane icon, and the existing track is shown in a Take Lane... there seems to be no way to remove the Take Lane again so that it's back to just a single track without Take Lanes.
 
Am I missing something?
 
Thanks.

You're not missing anything. Once you record a take to the track and expand the lanes, the blue coloring remains forever, until you remove all the lanes in the track.

Why would I not be able to restore the track as a single track, without the glowing blue take lanes icon? That icon should indicate if I'm using multiple take lanes for a track. If I'm returning to a single track... I really don't want that glowing blue take lane icon to remain, as it makes me think I have a track using multiple take lanes, when I actually do not.
 
Seems a better idea to only have the take lane icon glowing blue on tracks that actually still have multiple take lanes. Not on tracks where multiple clips are on a single track or take lane, or on tracks that are really only a single file, even.
 
Doesn't make sense to me that even just accidentally clicking the take lane icon means that you forever see the take lane icon as active.

I actually feel the same. I posted a feature request about it sometime during the X3 period, several months before the Features & Ideas forum was introduced. No improvements were made to Take lanes after that, so I decided to forget about the dim blue coloring. But then someone posted (almost) the same request in the F&I forum, so I voted for it.
http://forum.cakewalk.com/Better-indication-of-existing-lanes-m3170784.aspx