Other users can't edit the network connections
If you can edit a network connection but other users on your computer can't, you may have set the connection to be available to all users. This makes it so that everyone on the computer can connect using that connection, but only users are allowed to change its settings.
The reason for this is that, since everyone is affected if the settings are changed, only highly-trusted (admin) users should be allowed to modify the connection.
If other users really need to be able to change the connection themselves, make it so the connection is not set to be available to everyone on the computer. This way, everyone will be able to manage their own connection settings rather than relying on one set of shared, system-wide settings for the connection.
Make it so that the connection isn't shared any more
Click the network menu on the menu bar and click Edit Connections.
Find the connection you want everyone to be able to manage/edit themselves. Click to select it and then click Edit.
You will have to enter your admin password to change the connection. Only admin users can do this.
Uncheck Available to all users and click Save. Other users of the computer will now be able to manage the connection themselves.