我正在尝试从服务器上卸载ORDS，但无法正常工作。我正在尝试将其卸载，以便重新尝试安装。

卸载失败，并显示以下错误：

Enter the name of the database server [dbname]:dbname
Enter the database listen port [1521]:1521
Enter 1 to specify the database service name,or 2 to specify the database SID [1]:1
Enter the database service name [servicename]:servicename
Requires to login with administrator privileges to verify Oracle REST Data Services schema.

Enter the administrator username:sys as sysdba
Enter the database password for sys as sysdba:
Confirm password:
Mar 24,2020 3:16:47 PM oracle.dbtools.rt.config.setup.SchemaSetup verifyDBAUserConnection
WARNING: Failed to connect to user sys as sysdba jdbc:oracle:thin:@//dbname:1521/servicename 
IO Error: Unknown host specified 

如何更正此错误以卸载ORDS？