There's many (unfortunately) shareware programs that makes it possible to hide the tasks in the taskbar, not removing them, just hiding them.
image of the option : Hide taskbar items
I haven't been able to find a single small program that does only that... hiding the tasks.
And unfortunately I have no idea of how to make one myself.
It doesn't have to have a lot of options, in fact it doesn't have to have any options at all, just a way to quit/close if that's what the user want.