Business process task stuck

Hello,

Please note that in order to remove these tasks from the notifications panel, you need to find the exact business process iterations that created these tasks and cancel the processes.

Thanks for the reply Mira. I already tried this. I actually stopped all historic business processes on leads. But these are still stuck somehow. 

This are the only tasks still in "running" status:

Bas Kroes,

Please describe what exactly happens when you try to cancel these processes, what error do you receive?

Hi Mira, just to clear out, these are the only remaining business processes that are not connected to leads. So the ones that are still visible in my notification center should not be in this list and are already stopped/cancelled. Therefore I don't know how to get rid of the tasks.

Does that make it more clear?