Everyone should be killed off except for Rick, the redneck guy who is the good zombie killer, maybe Laurie because they need some women around, maybe the other chick in the farmhouse and Herschel. Can keep Glen I suppose. And you can keep Rick's wife and Carl.
T-bone, the chick that looks like Sinead Oconner, Herschel blonde daugheter. All have to go, and there are more characters coming I am sure.
That is the good thing, a show like this, you just add characters as they run into them on the apocolypic highway.