2004-2012 Canyon/Colorado Automatic can be flat towed IF it is 4wd. There is a neutral position in the transfer case.
If it is a 2wd, then GM says no. I don't see the 2wd listed in any of the dinghy guides either. If they are not listed, then they are generally not flat towable without modification. You'll need to try other options such as the tranny pump or driveline disconnect, if there is such a thing for rear wheel drive vehicles.
Check out
Motorhome.com's Dinghy Guides.
This is one of several reasons why we bought a 2012 4wd Canyon.
Hope that helps!