How do you delete Google Calendar goals?
Same Calendar Version as yours ( update released on 15/08/2016). Moto X Play 6.0.1

I created goals using goals option of app and am able to choose and delete. Screenshots below


First one shows goals for today and tomorrow
On pressing one of them it appears as in second one
Third one shows the Delete option on pressing the overflow (3 button) menu
Last one shows the options you are looking for