How do I change the weather city on my IPad homepage to my city rather than Cupertino?

Perhaps your refer to a Weather Widget. If so, touch-and-hold (i.e., long-touch) the Widget…

To change the displayed location to another city, select Edit Widget, tap Location then select the preferred city or Current Location.

If instead you are attempting to change the list of cities of interest within the Weather App itself - open the Weather App; within the associated sidebar you will see a list a locations for which a forecast has been configured. At top-right of the Weather sidebar, tap the ellipsis (“…”) icon - and from the menu tap Edit List. 

How do I delete a city that’s listed in my Weather app on my iPhone. Thank you.

No, it’s not the widget when I go press the widget to get into the Weather app I have several cities listed and I wanna delete the ones I no longer use. How do I do that please