Choosing the delete action will remove all existing runs in your run list, run the analysis and place the resulting run in the now empty run list. The only way you can recover the old run list following this action is to load an analysis file which has been saved prior to this action; that is if you are lucky enough to have one.
Choosing the cancel action returns you to the application without generating an analysis. This does not change anything. However, it also does not generate the analysis, the action which is what brought you here in the first place.
There is a more elegant solution to this problem which allows you as the user to maintain runs across what is referred to a CYCLE. This is slated to be implemented in future software releases.A more detailed explanation of this problem is contained in the user guide (which can be accessed from this application).