Deleting Instagram was one of the best decisions I've made in the past year. I won't say that there was a lot of toxicity or anything like that, but looking back at the amount of time I spent mindlessly scrolling through the app makes me feel sick. I feel like once social media can't eat up as much of your time, you have the option to fill that gap with literally anything better. Watch a show, get a hobby, make a good dinner, just something that isn't social media.
To answer your second question, just delete your apps and try not to open it on your browsers. I want to say delete your accounts because that's what ended up working for me, but I realize not everyone really wants to do that much right off of the bat, so just start small. Also I agree with Zoomie, try to fill up your schedule so that you're not left looking for something to do.