Creating an activity and ending it out from another activity

Hi,

I have a workflow in which I transition to two different activities from one activity. One of these activities continues the workflow and second one is a monitoring activity.

I can create the monitoring activity no problem but I m having trouble ending that activity from another activity. The activity continues to show in the task list.
Is there a way to delete or finish an activity from code?

In the screen shot I show the entire workflow after "Assign Contributors" activity I create the "Monitor" activity. I would like to end that activity(task) from the "Post Briefing Note" Activity which is the last activity in the list.

Thanks for you help in advance.