You will need to have Full Write Workflows to perform this action.
Navigate to the workflow you would like to edit. Then select "Edit workflow details" in the "Actions" menu in the upper right.
A pop up will appear where you can edit the details. See this article for details on the fields available. In addition, the following fields only appear when you edit in this way:
Enabled? - you can enable or disable a workflow from here. Once enabled, all processes and tasks will be running. This includes any triggers you have set up on the processes. Do not enable if there is more configuration to be done. If disabled, no automation will take place on any processes within the workflow.
Once you are done, click on "Save" to finish.
In addition to this, you can also reorder the processes by clicking on dragging on the three lines at the beginning of process.