Get friends on a platform quetz with 2 to 3 cannons and try to get the titan stuck, then have a few large storage chest on the quetz with cannon balls just in case and aim for the head with the cannon.
You hit it with cannons on a quetzal. Go for it’s head. It’s torpor won’t drain either so take your time. They can’t eat just stuff a platform saddle on the titan once KO’ed. You use daedons to heal it when it’s food level is low.
If you try taming these guys, tame a Quetzal first and equip it with a platform saddle. Then, put 2 storage boxes on it and a cannon. Make sure you make LOTS of cannon balls. Then, shoot the titan in the head.