Respec(t) Your Skills
If you need to reset your skill tree, you need to visit a Skill Mentor. This is now free for subscribers. If you respec frequently, you might want to consider buying the Legacy perk for Field Respecialization. It's 200K, but worth it to avoid traveling. There are Skill Mentors on the Fleets, and on the capital worlds.
Coruscant, in the Senate Commercial District beneath Senate Plaza.
On the Republic Fleet (Carrick Station)
In Kaas City on Dromund Kass:
On the Imperial Fleet (Vaiken Spacedock)