Sorry for my english.
I have project and modified workflow so that user must at first setup custom field "story points estimates" and then he can move task to "In progress"
But I can't understand. If I try to move task "to do" -> "in progress" without fullfill field I can see such error 
I see, that I can't move task, but also I can do it. How I can remove middle element.
Also I can move task to "in progress" by drop down menu in task. How I can disable this too?