-- Connect to emcli
$ORACLE_HOME/bin/emcli login -username=SYSMAN
-- Delete Agent from the machine:
$ORACLE_HOME/bin/emcli delete_target -name="<AGENT_SERVER_NAME:PORT>" -type="oracle_emd" -delete_monitored_targets -async
-- Delete specific target:
$ORACLE_HOME/bin/emcli delete_target -name="TARGET_NAME" -type="TARGET_TYPE"