I'm pretty sure that you can talk to your elemental leatherworking trainer and click the "i want to forget elemental leatherworking" button or something along those lines.
Not sure as to why you'd make the switch from elemental to tribal as a rogue though all things considered. Tribal LW adds to things like int, spirit, +healing/spell dmg, and other fairly useless stats (for rogues)
Elemental leatherworking has everything you'd need; Agility, stamina, attack power, crit rate, hit rate, etc.
So I wouldn't reccomend switching over to tribal, but if you really want to just talk to the trainer and ask.