Below are the steps for changing the sysman password for oracle 12c cloud control.

1. update the passwordn using emctl config

  syntax -  ./emctl config oms -change_repos_pwd -use_sys_pwd -sys_pwd <sys password>  -new_pwd < new sysman password> 

[email protected]:...ta/app/oracle/oms12cr5/oms/bin$ ./emctl config oms -change_repos_pwd -use_sys_pwd -sys_pwd oracle1234 -new_pwd oracle1234
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.

Changing passwords in backend ...
Passwords changed in backend successfully.
Updating repository password in Credential Store...
Successfully updated Repository password in Credential Store.
Restart all the OMSs using 'emctl stop oms -all' and 'emctl start oms'.
Successfully changed repository password.


2. Stop the OMS
[email protected]:...ta/app/oracle/oms12cr5/oms/bin$ ./emctl stop oms -all
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
Stopping WebTier...
WebTier Successfully Stopped
Stopping Oracle Management Server...
Oracle Management Server Successfully Stopped
AdminServer Successfully Stopped
Oracle Management Server is Down

[email protected]:...ta/app/oracle/oms12cr5/oms/bin$ ./emctl start oms
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
Starting Oracle Management Server...
Starting WebTier...
WebTier Successfully Started
Oracle Management Server Successfully Started
Oracle Management Server is Up

[email protected]:...ta/app/oracle/oms12cr5/oms/bin$
[email protected]:...ta/app/oracle/oms12cr5/oms/bin$ ./emctl status oms
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
WebTier is Up


cloud CLOUD