To delete a goal, swipe from right-to-left on the goal you wish to delete and tap on the red trash can button.
To delete multiple goals, first tap on "Edit" in the upper-right hand corner. Then select all of the goals you wish to delete and select the "Delete" icon in the Action bar at the bottom of the screen.
Please note: Deleting a Goal is permanent. If you wish to keep the Goal for future use, you can mark it as completed(Task), Formed(Habit), or Achieved(Dream) and later reactivate it.