Periodically it may be necessary to delete a WiFi network you have joined in the past. This knowledge base article explains how to forget a wifi network. Deleting or forgetting a Wi-Fi network on Mac is fairly simple, once you know where to look. 

 

1. On the finder bar at the top of your Mac's screen, click the Wi-Fi icon. 
2. 
3. Click Open Network Preferences.
   
   1. It's also possible to forget or delete a network via System Preferences. Click the Apple Logo in the top left corner of your Mac's screen, then click System Preferences > Network.
4. On the left-hand sidebar, click Wi-Fi.
5. 
6. Click Advanced.
7. Scroll through Preferred Networks to find the network you want to delete.
8. 
9.  Click the network, then click the minus (-) to forget it. 
10. Don't want to delete the network, but don't want to auto-join either? Click the tick box next to the network name and you can set your Mac to no longer auto-join the network whenever it's in range.
11. Repeat for as many networks as you want to remove.
    
    1. Want to remove all the networks at once? Press CMD+A on your keyboard to select all, then click the minus (-).
12. Click OK to save the changes.