I called Thankyou and they can see "multiple" expedia accounts, but only one shows up on thankyou.com
They told me the only thing they can do is combine accounts. They cannot remove the reference to the expedia account. Even if you close the expedia account, it will be in the system "forever."
So I called expedia and told them to reinstate own of my old acounts. That's done so now I will call TY again and ask them to combine that one with my TY master account.

What a mess