How do I eliminate a track's vibrato in X1 Essential?

What kind of a track are you talking about? Instrument? Audio?
 
Some kinds of instruments don't have a vibrato control. So it would be helpful to know more details about what you're trying to accomplish.
 
For audio, you could try a pitch correction plugin with a very hard setting. X1 Essential does not have V-Vocal so you'd have to find a third-party plugin.

AFAIK there is nothing bundled with Essential that can do it. You'll have to go to a third-party utility like Melodyne, unless somebody knows of a free/cheap alternative. The most widely-used freebie, GSnap, does not support vibrato reduction.

I save Finale files as midi files and bring them in to Sonar. I use mainly Garritan Concert and Marching Band 2 instruments. I'm getting vibrato on some tracks for instruments that didn't initially have it. I wonder if something in my midi save or in Sonar added the vibrato?

I'm getting vibrato on some tracks for instruments that didn't initially have it. I wonder if something in my midi save or in Sonar added the vibrato?

 
Do you see any controller activity in the Piano Roll View?  Sonar can't really "add" something like vibrato without instruction - and if it is a distinct vibrato, I doubt if it is caused by your interface.
 
Brian

Open the track in event view and look for Mod Wheel data.  That is the normal way vibrato is added.

I'll give these suggestions a try. Thanks.