Some options at various levels:

• Take the phone app off your home screen
• Make sure it’s not in your Firefox address bar’s suggested sites
• Log out on every platform when you’re done looking at it, so there’s even more friction to checking it
• Make a post there announcing you won’t use it any more, possibly why, and share better places people can keep in touch with you. (Then stop using it with any regularity)
• Help your immediate family (or friend group) setup a group chat on some other platform, and share updates with each other there

Individually making good choices is nice, but even better if you can help other people leave it behind.