Although I am not positive why you are not able to delete the joints as it states on the help page, there is an order of operations needed to achieve this condition in your analysis...
First, select and calculate all the beams except for one of the cross members.
Next, right click on each of the mustard colored joints that you want bonded to its adjacent beam. Then click on that adjacent beam.
Next, click calculate and the mustard color joints turn pink and the updated joints are shown with with and asterisks in the results list. This should give you your desired results
Thank you for this detailed explanation. It did help me a lot.