How to remove existing wireless network profile on Mac
Click the Apple menu then select System Preferences.
When the System Preferences screen appears, please go to Internet &Wireless section and click Network.
Under Network screen, please select Airport/WI-FI, and then click Advanced.
Under the Airport tab, select the network which you want to remove and click on button “-”. Then click OK.
Go back to Network page to select the network you want to reconnect by double clicking the network name.
Please type in the wireless password and click on OK.