How do you use your Sub-Tasks?

As i understand most of you are using kanboard as project specific. What i would like to do is to create a one project with my individual projects as tasks and use sub-tasks to follow their progress. So far so good. I would like to see all my projects under the same screen and also like to see the percentage of sub-tasks. Please see attached screenshot for your info.

What i would like to see is once i click the sub-task done, i would like it to hide when and not show on the list anymore. As an example, lets think that i have 40 sub-task and i already worked on sub-tasks between 20-35. it would be great to see the only remaining sub-tasks and hide the finished one. It seems like its not a skill for kanban for now but wanted to hear how you are managing this kind of projects. what is your approach?