Not a problem.. log on to the router.. http://192.168.0.1
you will be prompted for a password.. if you have not set one click on the username and enter admin.. then click ok.. there is no password on this model..
on the main page to the left on the very bottom you will see dhcp.. click it.. the page will refresh.. very top.. it says DHCP server.. disable that click apply.. then you should be set to go..
I would power cycle the system, removing the power cords for a min or so, just to make sure that the setting stick..