In recent versions it's impossible to remove connection between rail / road, as it demolish anything, not only expected way:
(http://mallorn.ii.uj.edu.pl/~amelek/work.JPG)
(http://mallorn.ii.uj.edu.pl/~amelek/result.JPG)
also, when you try to drag and destroy two unconnected elements of track, it will demolish track on target field (same as if you had used simple remove/destroy tool)
should work in 2984 again.