Delete Favorites on iPhone

Open Favorites and choose "Select" from the upper right (or for all of them, "Select All" at upper left) and then tap the circle with 3 dots at the lower right. That gives you a menu of additional choices. You can choose "Unfavorite."

Did that work for you?

There is no way to remove the favorite photos from the favorites album, but keep them marked with the heart ♡ as a favorite. The Favorites album is a smart album, based on all photos in the Photos library, showing automatically all photos marked as Favorites.

To remove a photo there you have either to delete it from Photos or to remove the Favorites heart.

Why do you want to remove the Favorites? Are you trying to save storage? The photos in Favorites are not duplicates. Photos can be in many albums without needing extra storage.

When you need to free storage you have to delete photos; removing from an album will not free storage.

To remove the photos from the Favorites album without deleting them from your iPhone, select the Favorites album, tap a photo and tab the "heart" icon in the toolbar at the bottom of the screen.