You can archive a finished project in a business process. To do that, use the Archive activity. It is used in the preconfigured project archiving process in the Projects app. By default, this process is started when the user clicks the Finish button on a project page with the In progress status.
You can use the activity in a custom business process. For example, place it on the process flow chart after the task for the project manager to make a decision to archive the project.
Before configuring the activity, create an App type variable in the process context and link it to the Projects app. In the process, the item of the Projects app that needs to be archived will be written to this variable.
After that, drag the Archive activity to the process diagram, place it where needed, and double-click on it. In the window that opens, select the variable you created.
If you want to make it possible to restore a project in the process, use the Restore from Archive activity.