Depends on what you're asking. If you're asking if you can prevent TPs from being converted, the answer is no (and I can't think of any reason you'd want to).

The only thing that checkbox does is automatically converts points without prompting. For example, if you're low on MTPs and train in a mental skill, you'll get an annoying popup asking if you want to convert points, and you have to do it every single time you train up a rank. Checking the box bypasses the popup question and automatically converts. There's no way to say no. You train in the skill and convert the TPs or you don't train in the skill and don't convert the TPs.