IPhone default weather app : I can't delete cities.

Question

iPhone default weather app : I can't delete cities.
I'm using iPhone 4S with latest updates of iOS.
In the default weahter app, I added several cities (Detroit, Seoul, Shanghai, etc) for the weather conditions but recently, I changed my mind that I need only the weather in my local city wherever I am.
So I decided to delete the cities I already registered, but checking after several hours after delete, the cities I deleted were shown up again automatically, I don't know why.
This is very annoying and this kind of weather app should work flawlessly because it's very simple.
I don't see iCloud backup this cities in the weather app, so I don't think this is synced, and if I delete cities, that is locally affected for my iPhone only, not other iPhone or iPad I have.
One potential problem I think is.. I found that the default weather app uses yahoo's weather service. When I clicked the trademark on the app, it directed me to Yahoo Korea site (yes, I live in South Korea), but Yahoo Korea's service discontinued 12/31/2012. Maybe, this is the issue, Yahoo Korea's service discontinue is causing this issue?

Answer 1

@LexSchellings I appreciate your advice on how to delete a city.  However if you read the thread that is not the problem.  We all know how to delete cities.  In fact most days I go into the weather app and delete cities I don't want.  The next day I come back and they have re-appeared.  This happens on my iphone (my Apple ID) but if I borrow my wife's iphone and her Apple ID (both phones are on IOS7) I can remove cities from her weather app
This proves to me
* That I know how to delete cities
* That my finger is not the problem since it seems to be compatible with iPhones in a pink case
* That there is a bug in the weather app [shock!]
This has been written about across a number of threads in Apple communities over IOS6 and IOS7.  Apple just ignore us.  I used to be a developer and the intermittent, doesn't happen all the time bugs are really irritating.  The best strategy as a development team is to find a device that does not cause the problem, "prove" it is fixed and move on.  That seems the be the current Apple strategy.
My real guess is that somewhere there is a record of the cities I want to see (perhaps created on an old phone or an old iPOD touch that shares the same apple ID) - when I delete a city, it stays away for a while but then my local app refers to this reference list and reinstates cities - not sure if that makes sense. (BTW I have gone back to my current iPod and tried deleting cities there but that doesn't help)