Depending what you have enabled as far as what contributes to the shipping rate (weight, sub-total, quantity, etc), change the conditions so that a rate would be impossible to match.
For example, if there is a weight range of 5-25, change it to 50000-250000. Since this row will now never be seen by the customer, you can also change the description by adding "(added 000)" to remind you what the original range was.