I'm pretty new to this, so forgive me if my terms and thoughts are screwy.
 
I wanted to grab a trumpet note off a Miles Davis cut, so I imported the audio file, selected, cut and pasted the clip I wanted, bounced it to a clip and trimmed it. All good.
 
But in my audio folder, this monstrously huge miles tune is sitting there, now for no reason at all. But if I delete the file, Sonar asks for it and warns me that clips that reference it will be silent if it is not there. I hit skip, and the whole project loads and plays fine. 
 
My question is this: How do I tell Sonar that I don't need the original Miles file anymore and it can stop pestering me to provide it? 
 
Minor issue, sure, but it's where I'm at. Small brain, small issues. 
 
Thanks.

That shouldn't be happening unless there's still a track/lane in the project that references the original audio file. Delete that track/lane, and the missing audio prompt should go away.

Brundlefly, I'm using X1 (producer expanded), so lanes do not yet exist in my universe. I have two tracks with clips from the original audio file, and those clips are all working fine when I remove the original audio file from the audio folder. There are no layers or takes or anything like that. The track where I originally placed the full Miles track (from which I clipped my clips) has been deleted. 
 
In short, the project plays perfectly when I tell Sonar to skip looking for the original audio file, so I can't figure why Sonar is still looking for it. Am I missing something?

Make sure you're showing all tracks, and show layers on audio tracks. Then hit Ctrl+End to see if the Now time finds the end of the original clip. I think it must still be in there somewhere. Or maybe you left of sliver of a clip referencing the original file after you cut out what you wanted...?

You may need to bounce that clip you cut out. As Sonar is non destructive if you cut or copy a section of imported audio the original file will still be there.

He said he did bounce and deleting the original file didn't hurt playback of those clips, so I think that's covered.

I wonder if it was deleted in the project or the projects audio folder. Doing the former will still leave the imported audio in the audio folder.

Is he saving by project folders or is the imported audio file also going into the global audio folder and still being referenced there.

Maybe there is a narrow piece of the original audio clip still remaining that is too small to be seen. Try zooming in and scrolling through the track. Selecting all might make it visible.
 

Maybe you could try to save the project to another location?
 
By doing this only the audio used in the project will be copied to the new location and (hopefully) Sonar will stop complaining over audio it can't find when you open the new project.
 
Worth a try anyway.

Thank you all for your thoughts. I took Kev's suggestion and selected all, then scrolled through the track with a magnifying glass, also bouncing everything to clips again. Somewhere in that process, I did what Sonar wanted me to do, and it no longer harasses me for the original track. 
 
It was a good learning experience for me. I didn't really understand things like the folder structure and the way Sonar handles audio clips before. It makes a lot more sense now. Again, thanks everyone.