Again, this may vary just slightly by device, but you can generally remove a saved network by going back into the same WiFi Network list you accessed before.
- Open your device's list of active wireless networks. Make sure WiFi is turned on.
- Select the name of the network (SSID) you want to remove.
- Long hold or click to open options for that network, then select "Forget" or "Remove" to remove the network.
You can use this to remove all saved networks if your device is attempting to connect to the wrong network, or as a way to reset WiFi if you are unable to connect.