Ok basic question:

How to delete a desktop activity?

I can see them in my activity list, but found no way to delete them...

using activity manager

picture http://linuxcrunch.com/sites/default/fi ... itcher.png

hover cashew, click activities and the activity manager will appear on bottom of screen
click the x at the top of selected activity to delete it, then confirm deletion

Humm, ok, got it.

In my case I only have the Delete red cross after pressing stop first...

I was looking for something like right-click -> delete...

Solved.