Many organizations have workflows with e-mails or that make updates to a record that sometimes need to be changed. Microsoft CRM does not allow you to make changes to a workflow you don't own. However, that doesn't mean you can't update the workflow, you will simply need to reassign ownership to yourself before doing so.
Navigate to Setting > Processes > Change the View to All Processes
If it is defaulting to My processes you won't be able to see all the options, just the processes you currently own.
Reassign Ownership From the Process List
You can select more than one workflow at once or a single workflow with this method.
*Important to note if selecting multiple workflows, reassignment deactivates a workflow so if you are reassigning more than one make sure to activate any that need to be active even if you don't get to editing right away.
Reassign Ownership from the Workflow (Process) Record
If you are looking at a workflow and realize a change needs to be made you can reassign it to yourself or someone else from within the process record.