If you travel regularly with your Mac or iOS device, you likely find yourself connecting to new Wi-Fi networks: at airports, in train stations, in hotels, restaurants, pubs, or at clients' offices. Whether you connect to these networks with your Mac, iPhone or iPad, miraculously, your devices will remember these networks and sync them via iCloud — so your other Apple products can access them too, if you use iCloud Keychain.
Your Apple device's ability to remember previously connected to networks can be both good and bad. While it means you don't have to search for or remember login credentials when you connect to a known Wi-Fi network on a different device, it can lead to a surfeit of Wi-Fi networks stored in your keychain and potentially allow you to unknowingly connect to a Wi-Fi network that might not be secure.
You can cull these Wi-Fi networks, but only on a Mac. Read on and we'll show you how to remove these Wi-Fi networks so your Macs and iOS devices forget them.
How to Remove Wi-Fi Networks from iPhone or iPad
While you cannot remove individual Wi-Fi networks from an iOS device, there is a nuclear option. If you tap Settings > General > Reset > Reset Network Settings, the iOS device deletes all your Wi-Fi networks and passwords, along with other network settings. However, this does not carry over to iCloud Keychain if you are using it, and the only way to fully delete these saved networks is on a Mac.
How to View and Remove Saved Wi-Fi Networks via Network Preferences
There are two ways you can view (and remove) saved Wi-Fi networks on a Mac. The first way is in the Mac's Network preferences.
To do this, open System Preferences, and then click Network. Select Wi-Fi in the sidebar, and then click Advanced. In the Wi-Fi tab, you will see a list of networks.
This list is mainly there so you can choose an order of preference for joining networks. You can drag the networks in the list so the preferred networks are at the top, but you can also delete networks by selecting it and then clicking the ‘—‘ (minus) button.
When you do this, your iCloud Keychain will update, and they will be eventually removed from all your devices that sync to the same iCloud account.
In some cases, you may not be able to remove Wi-Fi networks from the Network preferences, but you will be able to delete them from Keychain Access (see below for the second method to remove Wi-Fi networks).
From the image above, note the checkbox in the pane that lets you "Remember networks this computer has joined." If you don't want a Wi-Fi network to be saved to your Mac, and subsequently to iCloud Keychain, uncheck this setting.
How to View and Remove Saved Wi-Fi Networks via Keychain Access
The second way to remove saved networks is via Keychain Access. This app is located in the Utilities folder in your Applications folder, and it stores passwords, certificates, encryption/decryption keys, secure notes and more. One of the items it stores as "passwords" is the credentials you use to log into Wi-Fi networks; specifically, they are recorded as "AirPort network password."
To find these, click the search box at the top right of your Keychain Access window and type "AirPort." You'll see a number of items, and the Kind column shows them as AirPort base station password, AirPort Disk password, and AirPort network password. (You may not have items in all three categories.) The latter are your Wi-Fi network credentials.
Interestingly, when I look at my AirPort network passwords, I see many of those that are in the Network preferences, but not all. And some show as being in the iCloud keychain, while others are in the System keychain, even though they sync to and from my other devices. (For example, some of the networks I see on my Mac are those that I only connected to with my iPhone.) To delete any of these networks, click them, then press Delete, and click Delete in the confirmation dialog.
Note that any changes you make on your Mac will take time to propagate to other Macs, and to iOS devices.
It's a good idea to go through these networks from time to time. You may have connected to a network when you were traveling and not want to automatically connect to it again. Clearing out these networks will also prevent your Mac from automatically connecting to networks masquerading as legitimate, since the only identifying information for a Wi-Fi network is its SSID (or the name you see) and anyone can use the same network name, potentially leading you to connect to an insecure network.
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