You can use either Sybase Central or a DROP EXTERNLOGIN statement to delete an external login from the SQL Anywhere system tables.
Only the DBA or user who will be using the external login can delete an external login.
Connect to the host database from Sybase Central.
Open the Remote Servers folder.
In the left pane, select the remote server and then click the External Logins tab in the right pane.
Select the external login, and then choose File > Delete.
Connect to the host database from Interactive SQL.
Execute a DROP EXTERNLOGIN statement.
The following statement drops the external login for the local user fred created in the example above:
DROP EXTERNLOGIN fred TO RemoteASE;