How do i turn off wireless abilities in westell 7500

Presumably this is a wireless router.

In which case you need to access the router's setup screens (see manual or quick start leaflet for router's IP address and put that into the address bar of your browser).

You should be greeted by a login box -- Username is usually admin Password may be password or admin or something you chose (see router manual for default password).

Once in go to wireless settings and disable wireless -- usually by unticking a box that says something like Enable Wireless Access Point.