Buy a shitty phone. Also, this technique from dealing with cigarette addiction would help: change your brand. If you use iPhone, buy a budget $100 android with the smallest screen possible. If you use Android, buy an old iPhone 5. It'll work for banking apps but should be annoying enough that you won't use it so much.

Next, what is the website/app you most want to quit? Make quitting that your keystone. Fully commit to quitting that one website. For me it was reddit, and I haven't used it once in 4 or 5 months.

Then, uninstall all apps and switch to firefox. Install the leechblock addon, put a delay on all websites you want to stop using.

Bonus: switch to nextdns and block sites at the DNS level.

If any of that sounds like too much work, you need to ask whether you're really serious about tackling your addiction. Are you really serious about this? Yes? Then it's time for serious action. Small actions won't cut it. You need to send your subconscious a clear message that this is important to you.

Also, consider what kind of information you spend time absorbing. You are what you read/watch. Get some books on habit formation, willpower, psychology, read those in your downtime. The Power of Habit and Atomic Habits are great.