vendor number

Hello, I am trying to deactivate the authorization of my current edition of adobe digital reader on my computer as i have a new email address and a new adobe digital editions account.  my computer still recognizes the old account iwth the old email address.  when i attempt to deactivate this authorization i have to enter a "vendor login ID" and i have no idea what that is.  the library i am a member of has no idea either.  i cannot erase the authorization and cannot open books on my nook as it has the old email account.  what i need is a vendor login ID- what is that and how do i get it????