If you don't use a sales or service process the process bar at the top of the Lead, Opportunity and Case forms can be a little distracting and take away some valuable screen real estate.
Sure you could just minimize the bar in the lower right hand corner but that would require clicking on it every time and you still end up with the header remaining that shows the steps.
So the simplest way to remove the process bar is just to delete all the process steps. Once all the Stages and Steps are removed for the given form, the bar no longer shows up at all.
You can do so by opening the ellipsis menu at the top of the new form and selecting Edit Sales Process.
Delete each Stage associated with the entity until none remain.
The result is the new form sans process bar.