Well, for announcements, you can use AnnouncementsIgnore. I am working on a more comprehensive version that will block discussions and whatnot as well but it isn't quite ready yet.

many thanks

// Ignore all announcements except those from 12345 and 23456
window.announcementsIgnore = {
    option: 'opt-out-all',
    exceptWikiIds: [
        1149232
    ]
};

https://yandere-simulator.fandom.com/wiki/User:HarukaMurakami/common.js

thanks, i entered the above commands in user/common.js there, using their wikia ID using the value from city_ID.

Please see my previous post. Unless I misunderstood what you want, that code will do the opposite of what you want. You want to block the Yandere Simulator Wiki and allow all others, correct? Also, that will only help while on that wiki. If you want it to work while on other wikis, you need to use your global JS instead. Also, it looks like you didn't import the script; which you need to do for it to work. Here is what I think you want.

window.announcementsIgnore = {
    option: 'opt-in-all',
    exceptWikiIds: [
        1149232
    ]
};
importArticles({
    type: "script",
    articles: [
        "u:dev:MediaWiki:AnnouncementsIgnore.js"
    ]
});

AnnouncmentsIgnore doesn't work for Forum/Blog/Message Wall notifications, I believe. I think the OP wants to block envelope notification for a particular Forum thread and nothing to do with the bell which has Discussions and Announcements.

Oh. I see. I completely misread their earlier reply. My apologies. For that, shouldn't you be able to just stop following the thread? The only way wikis could force it to appear was using the highlight feature which has since been removed.

Well, that's the obvious choice...

i dont want any notifications from that wikia, they annoyingly host unnecessary forum meetings, and i get notified for no reasons. You understood what I meant. 

> not a particular forum threads. i want to block Yandere Simulator as a whole.

thanks, i inserted the codes https://community.fandom.com/wiki/User:HarukaMurakami/global.js

I don't think you understood me, but if the code above does what you want it doesn't matter.

Is it working?