How to remove cities from weather location list

Open the Weather app, tap the list icon at the bottom right of the screen (3 horizontal lines), slide the city that you want to delete to the left, tap the trash icon.

You can delete cities from weather location list by doing the following steps:

1. Open the 'Weather' app on your iphone
2. Click on the bottom right 'list' icon which should lead you to the list of cities
3. Swipe left on the location, then tap . Or, tap , then tap Edit List.

For more information on this, you can refer here: Check the weather on iPhone – Apple Support (UK)