convert a stereo track to mono?

I used a Roland R-26 recorder at a jam session this weekend and got some good sounding tracks off of it and want to mix it in Sonar.  The unit is actually a 4 track recorder with two integrated mic's and then 2 additional inputs for external mics/instruments.
 
I only had one cable to run from the mixing console and picked up the left channel out into one of the external inputs on the device to get more present vocals.  The room mics picked up all the instruments...but the vocals are usually way behind and hard to mix off of a recorder like this in a loud room.

Anyway, the track I pulled off the R-26 ended up being a stereo track but everything is panned to the left (since I was using the left output of the mackie console in the practice room).  
 
How can I turn the stereo track into a mono track?  

Bounce To Track(s), select Split Mono. This will create two tracks; one with the vox and one with the empty audio of the stereo track. Delete the empty track, delete or archive the original stereo track.
There may be other ways of doing this in the X series. I'm about a decade behind.