Declining is the most straightforward way to go, @Marsha25, but I will just mention something else if you want to save your "declines" for important wow-I-really-need-to-decline-this! scenarios. (You don't want too many declines on your record.) You can pre-approve inquiries such as this that aren't going anywhere with a note to the inquirer that says something like, "I know you have booked elsewhere, and completely understand, but the system requires me to pre-approve you to keep up my stats. Please just ignore it."