disclaimer: i personally believe that all of these should be undertaken to completely remove hp from your life. you can pick and choose which ones to get rid of though. i myself haven't done all of these yet, and i might never do some of them, so take all the time you need and remember that humans are inherently hypocritical:)
1) hp consumer
canon hp content: written by jk rowling
--movies and books: give them away
--block wizarding world site from ur search engine
--block harry potter content from discovery page(chrome/google users only)
fanon hp content: fanfiction
-ffn.net
--close and block website. i havent used this site in three to four years so i dont remember if you can save works or anything like that
-ao3.org
--unsubscribe from all hp related works
--delete hp related works from personal collections
--unsubscribe from authors who exclusively write hp content
--go through marked for later and delete all hp works
--go through bookmarks and delete all hp related works so you're not tempted to read them again
--recycle any fanwork printouts you've made. shred them first to provide added security concerning going through bin and attempting to get them back
--ask friends for fandoms to read in instead. this is your chance to get into anime(see description for fandoms list i personally enjoy)
-tumblr.com
--unfollow any authors who write exclusively for hp
--blacklist favourite hp ships tags(blacklist things you're susceptible to reading)
--leave any groups that are exclusively hp and request that no one in the group contact you with any hp content
--blacklist character tags as thoroughly as possible
--go through blogs who write hp and other fandoms and blacklist hp tags on their blog
--blacklist crossover content as thoroughly as possible
--ignore any hp writing contests/heavy fanwork posting times of year
-twitter
--block and mute jk rowling
--unfollow and block hp fanfic accounts
--block as many hp tags as possible
-instagram
--block hp accounts and do not go onto your discover page
we'll come back to instagram don't worry
-livejournal
--if you still use this site in 2021 you're a star. block the site from your search engine idk
fanon hp content: fanart
-instagram
--block hp accounts and do not go onto your discover page
--when scrolling feed, delete any posts related to hp. over time they will stop showing up
--dm any hp based mutuals and let them know that you're leaving the fandom, and ask that they do not contact you with hp content
-twitter
--all advice is the same. be especially vigilant during inktober
-youtube
--unfollow hp based youtubers
--if you watch plan with me content, be very careful around september plan with me's
--mark any hp related videos as "not interested" and "don't recommend channel"
real life!
--delete hp wallpapers, photos off of any devices
--take down hp decorations
--let friends/family members know that you will no longer be talking about hp and ask that they do not give you hp related gifts, up to and including a visit to universal studios
--give away hp memorabilia(cosplay outfits, wands, quidditch collectibles)
--change phone ringtone if necessary/get rid of hp phone charms
2) hp creator
--go onto wherever you post your fanworks and announce that you will no longer post harry potter works(cassiopeia721 made a great announcement on their work paradigm shift. skip directly to end notes on chapter 11. do not read the actual work stay strong)
--withdraw from hp fanwork competitions and let them know why
--take the time to throw yourself into other fandoms and create for them. consume a bunch of fanworks to get into that fandom's dynamics and energy. consume new canon content(again, see description for list of fandoms i like a lot)
--take a break from creating content at all if you've been particularly busy. artists in general tend to be neglectful of their mental health, but the hp fandom takes it to new fucking levels. take a break! evaluate whether your current level of production is something you wish to continue. evaluate whether or not you want to continue making fanwork at all, hp or otherwise. centre yourself and your mental wellbeing from now on and be upfront about your capabilities, available time, and levels of energy before and during agreements to make fanwork on commission, for competitions, or even for your own personal enjoyment. don't be afraid to quit.
--delete any hp wips. if you can't find them you won't be tempted to continue them.
3) self care after leaving the fandom
this may seem silly, but for a lot of people this has been their whole entire life, or a large enough portion of it that they can't let it go easily. if you're rude in the comments you're blocked. simple as that.
-take a content break from all fandoms. try to get into other hobbies, particularly ones that don't involve a screen. making things with your hands can be incredibly soothing if you remove the pressure to be perfect at it, or even good.
-journal about it! write a long letter about hp's impact on you as a person, and say a personal goodbye to as many aspects of hp as you can. be as sappy as you need, and make sure to ground why you're choosing to do this in each goodbye, or in the letter overall. this is not a matter of outgrowing the fandom. this is a matter of refusing to engage with any content that a deeply transphobic, transmisogynistic, and otherwise bigoted creator has made. you're leaving before you're ready and that's going to be painful, but if you've decided to leave, then you have to commit.
-evaluate your relationship with fandom. i might be weaning myself off of fandom content and just look at canon content for personal reasons. you can make it a smaller part of your life or leave entirely if you want.
ok that's it. bye and good luck