Greetings, alec46.
I see that you're unable to remove a city in the Weather application on your iPhone 8. I'm happy to help.
Delete built-in Apple apps on your iOS 11 device or Apple Watch -- Delete the Weather application, then restore it again. See if you're able to delete the city now.
- On your iOS device, touch and hold the app lightly until it jiggles. If the app doesn't jiggle, make sure that you're not pressing too hard.
- Tap on the app, then tap Delete.
- Press the Home button to finish.
If you have an Apple Watch, deleting an app from your iPhone also deletes that app from your Apple Watch.
- On your iOS device, go to the App Store.
- Search for the app. Make sure that you use the exact name of the app. Find the correct name of built-in apps.
- Tap to restore the app.
- Wait for the app to restore, then open it from your Home screen.
If you have an Apple Watch, restoring an app to your iPhone also restores that app to your Apple Watch.
Take care, and enjoy your day!