[oracle@MyHostName uninstallOEM]$ perl EMDeinstall.pl -mwHome /u01/app/oracle/middleware -stageLoc /home/oracle/uninstallOEM/ -force
Refer to /home/oracle/uninstallOEM/deinstall_2021-04-23_18-57-13.log for deinstall log
Substring valuye is /u01/app/oracle/gc_inst
This is a First OMS install. So, this deinstalls the OMS , Repository and Agent. Confirm (y/n)y
User confirmed for deinstallation.

Enter the SYS Password :
Enter the sysman Password :
Enter the Admin Server password :
dbConnectStr - (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=MyHostName.MyDomain.com)(PORT=1521)))(CONNECT_DATA=(SID=nprep)))

The command is /u01/app/oracle/middleware/bin/emctl stop oms

 Stopping oms............ Wait for the completion of the execution.
Oracle Enterprise Manager Cloud Control 13c Release 5
Copyright (c) 1996, 2021 Oracle Corporation.  All rights reserved.
Stopping Oracle Management Server...
Oracle Management Server Already Stopped
Oracle Management Server is Down
JVMD Engine is Down
 return value is : 0

The command is /u01/app/oracle/middleware/bin/omsca delete -full -OMSNAME EMGC_OMS1 -AS_USERNAME weblogic -REP_CONN_STR "(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=MyHostName.MyDomain.com)(PORT=1521)))(CONNECT_DATA=(SID=nprep)))" -force

The oms delete will take sometime. Wait for the completion of the execution. Don't abort the execution.

log4j:WARN No appenders could be found for logger (emctl.secure.oms.SecureOMSCmds).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Oracle Enterprise Manager Cloud Control 13c Release 13.5.0.0.0
Copyright (c) 1996, 2021, Oracle. All rights reserved.  
OMSCA-ERR:Administration Server is down. Using the -full option requires the Administration Server to be upon Server user password:
 return value is : 256

The OMS delete of EMGC_OMS1 has failed. Rectify the error and try again[oracle@MyHostName uninstallOEM]$
[oracle@MyHostName uninstallOEM]$ cd /u01/app/oracle/middleware/bin