Hello!

Please, check this article to see how to delete music with CopyTrans Manager : https://www.copytrans.net/support/delete-music-from-iphone/

Check also this article from Apple if you can't delete a song: https://support.apple.com/en-us/HT204343

Lastly, reach out to the support team at copytrans@copytrans.net, we'll be glad to help you!

Best regards

CopyTrans Team