./emca -deconfig dbconsole db -repos drop does not work

Question

I want to drop the existing dbconsole repository for em. but everytime when i run the comman, it doesn't work, and it tells me incorrect usage.
$ ./emca -deconfig dbconsole db -repos drop
Incorrect usage:
the help file is so the following: does that mean that I can't use the above command?
oracle.sysman.emcp.EMConfigAssistant [options] [list of parameters]
Options:
-a :configure for an ASM database
-b :configure for automatic backup
-c :configure a cluster database
-e <node> :remove a node from the cluster
-f <file> :specify the file name that contains parameter values
-h :help
-m :configure EM for a central agent
-n <node> :add a new node to the cluster
-r :skip creation of repository schema
-s :silent mode (no user prompts
-x <db> :deletion of a SID or DB
-RMI_PORT <port> :specify the RMI port for DB Control
-JMS_PORT <port> :specify the JMS port for DB Control
-AGENT_PORT <port> :specify the EM agent port
-DBCONSOLE_HTTP_PORT <port> :specify the DB Control HTTP port
The script will prompt for any required data that is not specified in a configuration file. The script always prompts for all required passwords. If you use a configuration file, the file may contain any of the following specifications, as shown, with the specified values correctly filled in:
Parameters for single instance databases:
HOST=<Database hostname>
SID=<Database SID>
PORT=<Listener port number>
ORACLE_HOME=<Database ORACLE_HOME>
LISTENER=<Listener name>
HOST_USER=<Host user name for automatic backup>
HOST_USER_PWD=<Host user password for automatic backup>
BACKUP_HOUR=<Automatic backup hour in number>
BACKUP_MINUTE=<Automatic backup minute in number>
ARCHIVE_LOG=<Archive log>
EMAIL_ADDRESS=<Email address for automatic notification>
MAIL_SERVER_NAME=<Email gateway for automatic notification>
ASM_OH=<ASM ORACLE_HOME>
ASM_SID=<ASM SID>
ASM_PORT=<ASM port>
ASM_USER_ROLE=<ASM user role>
ASM_USER_NAME=<ASM user name>
ASM_USER_PWD=<ASM user password>
EM_HOME=<Enterprise Manager ORACLE_HOME>
DBSNMP_PWD=<Password for dbsnmp>
SYSMAN_PWD=<Password for sysman>
SYS_PWD=<Password for sys>
Thanks.

Answer 1

Just checked and your command seems to be the correct one.
Are you in the correct Oracle Home? You need to be 'attached' to the database Oracle home:
$ cd $ORACLE_HOME/bin
$ ./emca -deconfig dbcontrol db -repos dropDid you stop dbconsole?
Try this sequence of commands:
$ cd $ORACLE_HOME/bin
$ ./emctl stop dbconsole
$ ## If it was not started then:
$ ./emca -config dbcontrol db -repos recreate
$ ./emca -deconfig dbcontrol db -repos drop?