Can I delete a primary domain cookie from a subdomain? I use one sign. Log out I want to delete the maindomain cookie
As far as I know, you cannot do this.
But could you just point out the main domain? (presumably you are already doing this to log in to get the primary domain cookie first)
I suspect that you will need to go to the parent domain, delete the cookie, and possibly redirect back to the child site (perhaps pass the returned url encoded in the query string).
not perfect and not verified / verified, but you can disable the cookie on the client (for example, using javascript). Not the smartest solution, but it could potentially work.