I understand, when I started planning my story I had at least two other characters in the main team, which were pointless and I decided to delete them.
Now, because you already have him in the story you can't just pretend he doesn't exist. Maybe you can:
- Keep trying to give him something interesting and work in his personality. The published story is just starting and for the readers I think his lack of depth is still not an issues. We still don't know him like you do.
-Make his lack of depth a plot point. Like, in some Adventure he and Selena have an argument because he is all about destroying the monsters and finish his job without thinking about the consequences. So he realizes that he was not really fighting for the good of people but to serve his ego ( if something like that) he can get humbled.
-He might walk away from the team. If he is hard to write and you think that he doesn't fit well in the long term he can just go away for some reason.
He might have an argument because everyone is so "unprofessional" and he thinks he can do a better job by himself. Or he needs to track down an enemy. Or he is on a special mission.
-He can die a hero (sorry Flare). He might sacrifice himself early in the story and serve as a motivator for the team to fight.
-He might get captured, brainwashed and cone back to attack the team. This can give him the inner struggle if being good deep down. And the team will have a conflict of fighting a friend.
I think there is still so much room to play with this character. But is hard to know what you really need without knowing more.