Your intent is not clear, and you have not provided any details. I'm going to go out on a limb and make some assumptions, some or all of which may be wrong. I'm probably way off base:
You are running Windows. You have connected to a WLAN. You want Windows to forget that network.
Go to Manage Wireless Networks and Remove or Forget that network. Or, in Windows 8, simply right click the WLAN in the list of available networks, and select Forget.
Or, perhaps you don't want your SSID to broadcast on your local WLAN, so it is not visible to anyone. The setting for that is in your router. Generally it can be found under Wireless settings in your router's interface.