Within the Workflows section of your studio profile, you can select the workflow template or the pencil icon for the workflow on the right.
Once you are in the workflow you wish to edit, simply click on any workflow item you want to change. This will allow you to edit the item itself. If you want to delete any item from the workflow, simply select the "x" to the right of the item to delete it.
You may also add workflow items to the workflow.
Any changes made to the workflow items/steps will only be applied to new workflows that are started for a client's session. Changes will not apply to already initiated workflows.