Properties can be deleted from the Properties page. Click on the Menu item "Properties". Then on the right side of the page click on the trash can next to the Property you'd like to delete.
To delete Properties in Bulk select all the Properties, with the box on the left side of the page, and then click on the "Delete" button at the top of the page.
To complete deletion you must type "Delete" into the dialog box to confirm deletion and then click on the "Delete" button.
After clicking on the "Delete" button the Property will be deleted from your account.