You can uninstall by tapping menu -> settings -> applications -> Manage Applications -> 1Weather and then select Uninstall.
If there is no uninstall, or only an uninstall updates or Disable option, the application was preinstalled on your device. Our applications are preinstalled by Sprint, TracFone, Straight Talk Assurance Wireless and others.
If the app is part of your device's factory software, you can't fully remove the app, but should be able to go to your device settings to applications tap on the app tap the "Disable" icon. You can then long-press and drag the app icon and/or widget to the trash on your home screen.