Jamf has an excellent KB article on how to deploy the McAfee ePO agent.
https://jamfnation.jamfsoftware.com/article.html?id=182
However, if you have already installed the unmanaged client you will need to remove the agent before reinstalling.
1) Uninstall the existing (stand-alone) agent using Casper Remote by running the following command:
/Library/McAfee/cma/uninstall.sh
2) Install the agent using Casper Remote and the following command:
/Library/Application\ Support/McAfee/install.sh -i
If you do not first uninstall the agent you will receive the following error:
"An higher or same version of the agent is already installed installer: Error - The installed version of the agent is already greater than or equal to this version. Installation cannot continue"