How to del the underlying plan?

solar plan was group, the line was group to.test intersect_with

In the Ruby API you get a reference to an entity and invoke its erase method. Without knowing the structure of your model I can’t give a Ruby snippet to get such a reference, as it would require knowing information such as what sort of entity is involved and what contains it.

It is also possible to create a shadow curve and then delete it with a lasso selection.