Varies. On mine one goes into 'apps', long press on the relevant icon until the menu appears, then choose uninstall. On my last phone I had to opt for uninstall prior to selecting the app icon. Play around, see what works.
If it is an app that came with the phone...
Select Force stop and then Disable — you won't be able to delete the app, but it will stop running on your phone, never to be seen again, until you do a factory reset