Yeah, but you know what? Once a member of the White Council, always a member of the White Council. Harry cannot just toss that, it is who he is ...
I mean,
yes... but also kinda
no, y'know?
Harry was trained by WC wizards, so that's the kind of magic he knows. Mab trained him to rely less upon his "traditional White Council" tools (the staff & rod &c), and his Winter powers seem to be able to operate in a different (more automatic/instinctive) mode than his WC training (in addition to just being an ice powerup to his prior magic). So he's ... diversifying. Gard used runes, and I bet Harry could use Gard's runes (with the right extra training). Plus he's a Starborn, so he's got this suite of non-WC abilities (about which we
still know very little, BTW!)
But the WC stuff is what he's known the longest, what he knows best. When he thinks about solving a problem, WC-trained magic are the methods he mostly thinks about.
So,
yes: he's "still White Council."
At the same time,
no.
The WC is basically just a social club. The rules of the club say that the club gets to say who is/isn't a member, and the club has kicked out Harry Dresden. He can't show up to vote, or debate internal WC matters.
If he does show up, it would need to be under the auspices of one of his other roles -- the WC would let the Winter Knight come address them, for example, on a matter of White Council / Winterfae diplomacy.
It's not as letter-of-the-law cut&dried as Mab's Unseelie Accords, but it's still a matter of following the rules, and the rules say:
no, Harry
isn't a member of the White Council.
I have a WAG, though, that the
Warden of Demonreach is actually the person who is in charge of the WC's "
Wardens" (the same term "Warden" being used for both just seems like too much a coincidence, particularly since both the White Council itself and the prison on the island were set up by OG Merlin). I look forward to a Big Reveal where the WC learns that their
entire security / military apparatus belongs to Harry Dresden...