There are a lot of "hacks" in this thread (put your phone in grayscale, put variable reward apps in a folder, turn off fingerprint sensor) but in my experience the mindset is by far the most important part. What's worked for me (and the article talks about this too) is viewing my phone as a tool with a limited set of functionality. For me, that functionality is: calls, texts, Google maps, Spotify, Audible, podcasts,…
When my dad decided to quit smoking, he didn't throw out the pack of cigarettes he was currently in the middle of. Instead, he put them up on the shelf next to his work desk. The pack wasn't totally in his face, nor was it out of sight. Despite the visual reminder being present, he broke his years' long pack-a-day habit. Eventually - long after he stopped smoking - he threw the pack out, as part of his usual housekee…
If you can not use it when it is there, you've really won.