If you don't want to have one of your link trees anymore, you can delete it at any time. Simply go to My Link Trees on your account and click on the gear icon of the link tree page you want to delete. There, you'll find the "Danger Zone" with a Delete button in it.
Please note that if you delete your link tree, you'll need to create a new one from scratch. You can also create, customize and delete as many link trees as you may wish.