To illustrate deleting a variation we will first save a variation with a different name and then delete it. So first open the Variation French-e5. Then use the file menu to save it as FrenchAdvance.
You will see this dialog:
We can now delete a line by first selecting the line by double clicking in the 4th column on Nc6. You can then use the Variation - Delete Line menu or the Delete Line toolbar button:
You will see this dialog:
We can now delete a Variation using the Variation - Delete menu or the Delete Variation toolbar button:
You will see this dialog: