How do I delete music from an iphone 4s

Swipe the song towards left to bring up a red red DELETE button. Tap the button to delete.

I used this as well but there are about 10 more than I'm wanting off of my sons phone that are inappropriate due to his age that will not come off no matter what I do. I downloaded some music on to my phone and it automatically went straight to his phone even though I have restrictions on it. I have tried everything... unfortunately even to the point of deleting all of his music on his phone but the remaining 10 will not come off no matter what I do... is there any other way around this? I turned off the icloud, etc to his phone as well but it is still doing it even if I do not plug it in to the pc. 😟