Music added to my phone

hi,

i have an iPhone 5, recently i was looking in my music folder and i have all this music that i did not sync to any playlist or my phone.

this music is in my itunes library, as it is my dad's and brother's music

when i open their music, it has an icloud option and about half of it, i cannot play (the song is grey not black)

i can't figure out how to delete them, as i do not want them

i tried looking in "music" when i hooked my phone up to the computer, however none of the artists are selected to sync etc

i also tried downloading them to icloud, hoping it would delete, however it didnt work

should i try tricking the phone, by syncing the music and then deleting it??

how do i delete them from my phone?

will a system restore work?

any help is appreciated! thanks!