You're behind the times, even logging in isn't sufficient now. You have to reset to old reddit in preferences now every time you log in.

More reasons to never return.

shreddit costs money now, but Power Delete Suite will still let you delete your post history on the way out.

https://github.com/j0be/PowerDeleteSuite

At present it only works in a Chromium-based browser.

Probably it's not really deleted but at least it stops your posts from adding value to the reddit's public-facing side.

I use LibRedirect when I have to go there. https://redlib.catsarch.com/ is my preferred frontend.

it still works on waterfox, and other forks. on mobile. i use sink it extensions, or yeoldreddit(and the old reddit switcher) the extension makes old reddit usable on mobile.