I know you probably have an idea of how you're going to remove him, but I figured I mention something.
Remember that there was another time that White was going to leave for something or something came up and his character had to disappear for a while? In that situation, you had said that he had decided to leave the group and go back to his clinic or whatever. Maybe you could have him do that again instead of needing to kill off his character?
It's up to you, but I just figured I should at least make mention of it.