Why can't tu go into the imperial gaurd places even though tu are know as the Champion and still can't be in guard bartracks and stuff like that?

do tu mean champion of the arena?

Because thats how it is no matter what tu do they wont allow it but on some occasions the guards don't ask me to leave at all!!!

If tu mean the Imperial Palace and the other areas like Ocato's room tu have to do the Theives Guild quest but if tu mean the reagular Barracks then idk but tu can illigaly ^_^

I think because the politics of the monarchy,the kings o Septims are at the parte superior, arriba so they have the
ability to use the whole tower floor 1-5,Ocato 1-3,you 1-2.

because tu are just a fighter not a guard

I dont know probably its A glitch o something xD