[russell]

Ordinarily I would agree with itbeho and advise you to move on with minimum fuss. However, given that you are paying the hosting bills, you probably have the right and obligation to shut the thing down gracefully, perhaps with a month's warning to the users. It does seem reasonable to answer any emails saying that you have not been contracted to provide support. I think it is best no to mention that you havent been paid. It is probably wise to contact a lawyer, because I am certainly not one.