How do I delete my iCloud account from iPhone 6

You need to use your original Apple ID. What problems were you having while downloading? Were you being told your Apple ID was locked or disabled? More information would help.

Apple ID is locked or disabled

If necessary, contact iTunes Support. Scroll to the bottom of the page in the 2nd link.

iTunes Support

iTunes Support – world wide

All content acquired with an Apple ID is forever tied to that Apple ID. Making another Apple ID was not the correct step to take.

You now have 2 separate Apple IDs and they can't be combined.

If by "trouble downloading" you mean you forgot your password, you will have to reset it to have access to your old music.

See http://iforgot.apple.com