Answer:
The simplest way to achieve this is to select the "Save File As" option in the "File" drop-down menu. In the following dialog box, unselect Results.
Both images show how the size of the file without results is reduced.
The results of the current model can also be deleted using the drop-down menu "Results → Available Results".
Another possibility is to right-click the "Results" entry in the Data Navigator and select the "Delete All Results" option.
Also, you can just shift a node in the model and thus delete all results. Then, use the Undo function to move the node back to its previous position. Now, save the model without the results.