Mirrored DB on Restoring state after removing Mirroing also
That is normal. When you setup a database mirroring the mirror database is on no recovery/restoring mode and copies and run transaction executed on primary server. Then when you remove the database mirroring you just stopped those transaction to be transferred and nothing is happened to bring it back to recovery mode. If you want your secondary (mirror) database to be active you have to execute.

      RESTORE DATABASE YourDatabaseName  WITH RECOVERY