I can't delete songs on my Iphone?

So I have had an Iphone 4 for a while, and my father has been putting all his music on him family account. All of that music was going on my phone each sync. I broke off from the family account and still had all the songs. When I synced onto my new account, if hit "sync and erase" it was suppose to get rid of that music, but some of it just stayed on. I synced my music onto it, and it just added to some of that music. Some of the songs I could delete by just dragging my finger across the delete button and doing it song by song, but some of those songs have a little cloud symbol next to it, and it wouldn't let me erase them. Some or those songs have also latched onto my itunes music. What's going on and how do I delete the fracking songs?!

It needs to be connected to iTunes

Connect it to itunes then open it and select the music to delete