So, there are a few other websites you can publish fanfics on (fanfiction.net and archiveofourown.org) other than Wattpad. On Wattpad, your fanfic can be taken down since their terms aren't quite fanfic-allowed, I don't think, but I didn't look into it initially when I was younger and publishing fanfics on here. The worst that they do, I think, is take your book down (deleting it from your drafts, which happened to me and a friend a few years back - not sure if it's the same here). If you do go ahead and post it, definitely make a disclaimer.
However! What I really recommend you do is check out archiveofourown.org which is a non-for-profit website full of fanfics with an amazing tagging system and community. It's where I post my fanfics for the most part, especially as they're primarily for fanfics and will protect your rights as well. Sometimes, there's a bit of discourse over the fact they run a fundraiser and things - but they tell you what they do with that money since it's all run by volunteers and they're actually really good. 10/10 would recommend! Hopefully that helps! Sorry for the late message as well, haven't been going through my notifications really.