As I obviously want to have a correctly defined board outline I don’t need the four segments marked with yellow crosses.

I want something like this in the marked areas instead:

But I have no clue how I can delete the unnecessary segments. As far as I can see I neither can delete segments (just nodes) nor break the outline at a certain node.
Is there an easier way to do this than completely redrawing the outline from scratch?
Edge Chromium
87.0.664.47
Windows
10
EasyEDA
6.4.7