Hello GD,
Great question, as it is a Samsung phone they baked it into the operating system without allowing you to completely remove the app. They do not offer a solution to uninstall the application, only disabling it is your solution. As your phone is a bit older, people have spent more time with it and it has been discovered you can remove Bixby without rooting your phone. If you click “proceed with caution” in the next sentence, there are some steps you could take however if you do, please proceed with caution as you can ruin your phone. Might be something fun to try once you upgrade phones.