Can't delete songs on iPhone with iOS7?

So I can delete some songs. But others won't let me delete them at all. I have an iPhone 4S by the way. But I have songs that got put on my phone that aren't on my iTunes on my Macbook bc they came from my brother's iPod. Those are some I can't delete. But some songs I can't even CLICK on! & those are the ones I can't delete. How can I get these songs off my phone completely? Or how can i just delete all the music off my phone & re-sync the music I want? Please help!

As you want to delete songs from your iphone but you mentioned that the songs were not getting deleted due to some technical problem i have an idea which might help you make a backup of your memory card and save all your collection in your pc and then format your iphone memory card all the songs and the content will be deleted automatically and as you made a backup copy use it to restore the songs you used to listen. I hope my idea works