How can I assign a short-cut to the "remove track(s)" command? I cannot find it in the list.

Preferences > Customization > Keyboard Shortcuts.
 
Area: Track View
Scroll down to Tracks|Delete Track(s)
 
Assign this to the keybinding of your choice
 

Delete works well. 

Thanks, guys!
 
Then I think I found a bug. I'm using the German version of Sonar Platinum, and the search filter does not find the shortcut, no matter what I enter there.
 
The German translation of the item is "Spuren|Spur(en) löschen". I tried "Spur", "Spuren", "löschen", and all the English versions (track, tracks, delete, remove, ...), but nothing matched.