I like most people I assume I created 3 characters when the vanilla servers came out. Currently I’m on Whitemane which is listed as Full. If I deleted one of my characters would that free up a slot for my wife to quickly create a character on there?
No. Realm status is based on overall concurrency, it isn’t a specific 100/100 cap.
That said, full doesn’t necessarily mean prohibited from character creation. Is your wife getting an error when she tries to make a character on her account?
I did want to note that several realms are considered Full at the moment and our Devs expect you will see a queue time, especially in the beginning. They have recommended perhaps going to a lower population realm, which may solve the issue.