Hi neville82,
I understand that you would like to lock your wireless printer's signal. I will try my best to help you with this issue. As long as you have a password on your wireless network you do not have to worry about the printer's wireless signal as it will only be accessible through your network. If you have concerns with this you can contact your wireless network supplier and they could help you set up MAC filtering on your router.
MAC Filtering refers to a security access control method whereby the 48-bit address assigned to each network card is used to determine access to the network. MAC addresses are serial numbers embedded within a piece of hardware, unlike an IP address, it can't be changed. Every network card has it's own MAC address, therefore, if you use MAC address filtering, only those specific pieces of hardware will have access to your network.
I hope this helps, let me know.
Thank you,