You can change the original name of a diagram version in the Under review and Publications panes by selecting the diagram item there and pressing the Rename button in the Action group of the Home tab. You can also right mouse click the selected diagram and select the Rename item from the pop-up menu.
The Rename dialog will be open where you can type a new name of the diagram.
The new name must be unique in the whole Under review list or in the embedding published folder, respectively. Renaming is an undoable operation.
It is important to understand that in the Engage Process Publisher you do not rename the diagram but only its selected version. Thus, if a modeler submits for publication the diagram called, e.g., Production process and you decide to publish it but under a new name, e.g., Car production process then users of the Engage Process Viewer will see it as Car production process but for a modeler it will be still called Production process. Moreover, if a modeler submits for publication a new version of this process you will see it as Production process in the Under review pane. It is your responsibility to recognize that it is the same process. To be sure you can check the Submitted as diagram property of the both versions.
Now, if you decide to publish the new version of this process the tool will recognize that the submitted Production process and the published Car production process are two versions of the same process and you will be asked if the new version should also get the old version name.
Thus, you should be very careful with renaming the submitted diagrams.