The Mobile VPN with SSL client does not have an option to delete cached server addresses
After you connect to a server with Mobile VPN with SSL, the DNS name or IP address of that server will always appear as a cached option in your Mobile VPN with SSL client. The client does not have a user option to delete cached server addresses.
To delete cached server entries on a Windows computer, you must modify the registry.
Warning: Editing registry keys can be risky. Do not try this unless you are very comfortable with the Registry Editor and you know how to assess the potential risks. We recommend that you create a backup before you make any modifications to the registry.
1) Open Registry Editor. Search for "regedit" and open as administrator
2) Go to HKEY_CURRENT_USER\SOFTWARE\WatchGuard\SSLVPNClient\Settings
3) Double click on "Server" and clear the server entries that are not needed
To delete cached server entries on a macOS computer, delete the file ~/Library/Preferences/com.watchguard.sslvpn.plist and reboot your macOS system.