Instructions
Maintain a safe distance from the Wraith. Although its cannon is extremely powerful, the range is somewhat limited. If possible, get to higher ground because it will be more difficult for the Wraith to attack you.
Use a Sniper Rifle to disengage the hatch from the front of the Wraith. Keep firing until it breaks off to reveal the driver. Shoot the driver to prevent the Wraith from attacking and moving around. Once this happens, you can safely approach the Wraith for a few moments -- enemy players will get into empty vehicles and start attacking with them, so use caution.
Lob sticky plasma grenades at the Wraith. You have to be fairly accurate with the grenades to make them stick. The area of affected damage does not do much to destroy the Wraith, but if you can make one stick, it should put a pretty big dent in the armor.
Use heavy artillery like the Rocket Launcher, Spartan Laser or Fuel Rod Cannon against the Wraith. These are the most powerful hand-held weapons in the game, so they do a lot of damage, even to large, armored vehicles, such as Wraiths. For maximum damage, aim at the glowing mass at the back of the Wraith.
Use another vehicle to launch an attack on the Wraith. Ghosts are particularly useful because they are considerably faster than a Wraith. Deliver an onslaught of plasma fire until the Wraith is destroyed.