I need to know how to get someone else’s Apple ID off my phone I cannot update anything her email keeps popping up

Check the App Store and iTunes Store to see if there are any updates for apps/purchases. A request for another Apple ID password is often caused by updates to apps/purchases that were made when using the other ID. Those purchases are tied to the other ID and can't be transferred. One option is to delete the apps/purchases made by the other ID and download them using the new ID if desired. If necessary, check your purchases history to see which apps/purchases weren’t made by the current ID. 

Purchase History Review

Is this a used iPhone?

ASC - Late 2012 Mac mini, macOS 10.14.6; Watch, series 3 cellular, watchOS 5.3; iPad Air 2 & iPhone 8+, iOS 12.4; TV 4th Gen, tvOS 12.4;  HomePods, audioOS 12.4 and Airport Express w/ Airplay 2