A quick guide in Final Fantasy XV on how you can defeat the giant Titan, please keep in mind this is the XBOX one guide but I found that it is also helpful for PS4 players. The key to bringing down the Titan is to not actually defeat him but to keep evading his attacks.
The Titan is too big and too strong for you to defeat at your current level. What you must do is stand in the center position and have your camera angled up so you can see his arm movements. Keep evading his attacks until you see a cut scene with Ignis pretty much finishing the fight for you.
When it comes to the Imperial forces I would eliminate them quickly so they don’t get in your way. Once you defeat them go back to the center and make sure your camera is angled towards his arm which is his primary attack. Please enjoy the video above for a better understanding on how I got past the Titan.