Not knowing your ePO version, but assuming 4.6.0 as it's the most frequent used presently - This is covered in the ePO product guide under the section "Changing SQL Server information"
Extract follows below:
You can use the web page at https://servername:port/core/config to adjust any database configuration file information that used to be done with the Cfgnaims.exe file.
Things to know about this page:
• Authentication — If the database is up, this page uses normal McAfee ePO user authentication and only a global administrator can access it. If the database is down, a connection is required from the system running the SQL server.
• The McAfee ePO server must be restarted for any configuration changes to take effect.
• As a last resort, you might edit the configuration file (<ePO installation directory>server\conf\orion\db.properties) by hand, put in the plaintext password, start the server, then use the config page to re-edit the db config, which stores the encrypted version of the passphrase.
1 Log on to ePolicy Orchestrator with global administrator credentials.
2 Type the following URL in the browser's address field. https://servername:port/core/config
3 On the Configure Database Settings page, change the credentials or SQL Server information, as needed.
4 Click OK when done.
5 Restart the system or ePolicy Orchestrator services to apply the changes.
Thanks for your help.