Gosh, I'm never in favor of curtailing the royalties. LOL In fact, I was so distressed that my Sim lost all 13 albums and the seven songs he wrote, hence no royalties coming in, that I rolled back to an earlier save when these things were still intact. Problem was I removed the Mods folder to patch, and after I thought I had dragged it back into the Sims4 folder, it turned out to be empty. I unwittingly played the game for a bit and of course saved the progress, which was the clincher. If you save a game without the needed mod it can remove stuff the mod gives. OOFFDDAA. Had I only noticed earlier the mod wasn't where it was supposed to be. Oh, well, all's well that ends well. Happily, I found the copied Mods folder with all mods accounted for. Phew!
As for stopping the royalties, eventually they stop on their own, at least with the songs. You can only license a song once a week. If you're talking about songs, once the royalties stop, just don't license it again or any other song and voilà problem solved.