Have you ever developed a workflow, put it into production, and then needed to make edits/updates? How do you test the new process without overwriting important files being created by your workflow?
You could delete the connections to the output tools, and then reconnect when you're ready. Or, you can do it the easy way and use the Runtime setting in the Workflow Configuration options.
Click in the blank space in your canvas to bring up the Workflow - Configuration options, and click on the Runtime tab. At the bottom you'll see the option to Disable All Tools that Write an Output:
After enabling this option, you'll notice the tools that write output in your workflow are greyed out:
Notice that only the tools that write output (Output Data and Render) are greyed out, the Browse tools are not. If you want to disable the browse tools, there is another setting on the same tab for that option:
This will have the same effect on the Browse tools, making it so they will not write out any temp files:
You can use these settings in any combination you'd like to achieve the desired result.