Modify a view title family to only use the title parameter (remove the scale and detail number). Then load that family and assign it to a new viewport type. Swap out any existing viewports that you want with this new viewport type.

Remember, even though you aren't showing a detail number there is still one associated with the viewport. If you add one of these viewports in between others you'll need to change the detail number so you can number the others sequentially. One way would be to use letters for the number instead of numbers if you normally use numbers. You could also number them really high...like 100 since you're not likely to put 99 viewports on a single sheet right?