Everyone gives this advice: put your phone away before bed. I knew it for years and never did it. The advice wasn't wrong, nobody ever explained the "how."
The problem is the environment, not willpower
If the phone is within reach, I open it. Things changed once I stopped treating this as a willpower problem. Physically removing the phone from the bedroom worked far better than trying to just resist it.
What actually worked for me
I moved my alarm to a separate clock, because "I need it for the alarm" was my most-used excuse. The phone charges in the kitchen now. I leave something concrete to hold for the last half hour, a book works, but sound made the real difference for me. Putting on an ambient track and dimming the lights cuts my urge to reach for the phone, mostly because my hands are already occupied with something.
The first three nights are the hardest
The first night without a phone in bed feels strange, your hand keeps looking for something. That feeling mostly fades by the third night. Give yourself a week, don't expect to get it perfect on night one.
You don't have to delete anything
You don't need to do anything drastic like deleting social apps. You just need the phone to not be physically reachable during that last half hour. Cutting access is a lot easier than trying to summon more willpower.