Remixing a song without permission is technically a "bootleg." To release a remix commercially, you typically need written permission from the copyright holder.
Re-harmonize the vocals by writing new chord progressions or changing the genre (e.g., turning a pop song into a House track). remixpacksclub
Here’s a short write-up for , written as if for a blog, music production forum, or promotional page. Remixing a song without permission is technically a "bootleg