You can go into the LiveCycle Administration Console and select Services > LiveCycle Process Management ES. There are tools to terminate your processes. For example, you can select Process Search and then select the name of your process and terminate the assocated instance of the process. There are other tools but you can read about at http://www.adobe.com/go/learn_lc_adminProcessMgmt_82.
I had already terminated them. I found the tool here: C:\Program Files\Adobe\LiveCycle ES\Workbench ES 8.2\LiveCycle_ES_SDK\misc\Foundation\ProcessPurgeTool although I could not get it to work with spaces in the path and moved it.
If I do a search for tasks, I still get them associated with processes that do not exist. In task history in Workspace, I also show all the process names even though there is no longer any data for them.
Something is messed up with process and/or task termination through AdminUI. I have had to go into the DB, specifically, process instance and action instance tables and change the status on "hung" tasks to get them "terminated"