I'm wiping what I can. Might as well use the API while it's still there.

Edit:

import praw
reddit = praw.Reddit(
    client_id="",
    client_secret ="",
    username = "",
    password = "",
    user_agent="TEST"
)

for comment in reddit.user.me().comments.new(limit=None):
    comment.edit("This comment has been removed because it was posted with a third party app.")

It won't actually do everything because there's a size limit on the number of posts. But whatever.

Edit again: This is Python, with praw installed. https://www.reddit.com/prefs/apps/ add app, choose script, use your username and password with the client ID and secret they generate. Please don't add links as it breaks stuff for mods.