Other iTunes accounts have downloaded their music to my iPad. I have deleted them and have ghost tracks/data?

My Dad and a couple others bought music on my iPad using their iTunes accounts. I have deleted the albums as I don't want them anymore. They don't not show on the iPad, but when I plug it into iTunes and look at what "What's on my iPad" it has the albums and songs bought, but they are greyed out. I delete them, and then when I plug my iPad in again and they re-appear. This is doing my head in, I don't know how to stop it. Someone please help! https://www.dropbox.com/s/06ufu5jp0xptrbl/image.jpg

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