how do i unpark a domain from sedo?
i simply deleted the domain entry from domain management
control panel, and changed its dns setting. is that right?

but for some reason, the sedo entry for the deleted domain is
still there, and i can no longer do anything about it.
when i click it, it says "the domain XXXX could not be found".

is that normal?

Maybe it's too soon after you changed the DNS settings for your ISP to have picked up the change. Wait 24 hours and see what happens.