There are two methods available for deleting a goal
First, from the goals list display, complete a swipe action on the required goal. By default, this is a swipe to the left.

Alternatively, click over a goal entry in the goals list to open the ‘Edit Goal’ form. A ‘Delete’ button can be found at the bottom right of the form. Click on this button to delete the goal.
Once deleted, a goal cannot be recovered.