I would stop Openfire, edit /openfire/conf/openfire.xml, uncomment
<authorizedUsernames></authorizedUsernames> and add my user to it like
<authorizedUsernames>wroot</authorizedUsernames>
if there is no such tag, then one can add this below </adminConsole> :
<admin>
<authorizedUsernames>wroot</authorizedUsernames>
</admin>
Then would start Openfire and login with user wroot to Admin Console and then maybe would try adding admin user back (never tried, not sure if one ca add it this way). Then would remove admin privileges from user wroot.
Another option would be to rerun a setup, maybe it will add admin acc back when specifying admin password.