Remove one song from iTunes account
The song you bought from iTunes Store is not yet downloaded into your iPhone, but will be streamed from iTunes while playing.

There is no option to cancel the purchase and remove the song - from your iPhone. But you can do that from iTunes, from your PC or Mac. Please refer to this to find more about how this request can be made. 


Launch iTunes on your PC or Mac.
Click on your name at the top and select Account Info.
Enter password when prompted.
Click on See All under Purchase History.
Click on the arrow next to the group that contains the
purchase you'd like a refund for.
Click on Report a Problem next to the single purchase you'd like a
refund for, unless there is only one, then you may use the large
Report a Problem button.
You will be routed to Apple's website. 
Follow the steps after signing in and request the Refund option and
explain why.