Delete file from server based on database query asp.net vb

I have a file folder that contains pdf files. The sql database is not directly related to the files. For example, I have “Invoice_co_355_24636.pdf” and “Invoice_co_355_25127.pdf” in the Invoices folder. I query the database and find that Invoice “24636” is not paid and “25127” is marked paid in full, so I would like to delete “Invoice_co_355_25127.pdf” at that point since it is paid.