My daughter installed "what's app" on my phone so she could reach me in an emergency. She left for Africa end of February. Flew to Ethiopia ,same plane as that that crashed there a week later. Climbed Kilamanjaro in Tanzania and backpacked from country to country for 73 days. Left Capetown a few days ago and is now in Paris. God knows what's next. I want to get this app off my phone. In runs down very quickly. Google is updating their stuff daily and I can't stop it. I'm constantly charging it. Never was like this until this app.
Thomas - if your daughter installed the app, it is easily disabled or removed - if you have an Android phone, go to "settings" then "apps" and look through the list for the name of the app. When you select it you will have two options, probably "force stop" or "disable" and possibly "uninstall". If you're on an iPhone, then you're on your own - I have an Android.
If the app came preinstalled with the phone, then the best you can hope for, as far as I know, is to disable it as the preinstalled apps are harder to uninstall.