You are looking at the US post.
This is from the EU post:
Wrath of the Lich King Classic Season 6 Ends 30 May
The second Wrath Classic PvP season will end at 21:00 BST on 30 May.
21:00 BST May 30 is later tonight. I think the realms are on CEST, which is BST+1 so it’s 10PM tonight.