My account is 15 years old and I've been manually doing this for some time now.
A few years ago, I had a comment get upvoted to the top of a popular thread in a major sub, but it had some mildly identifiable information about myself, so I deleted it.
A few months later, Reddit had this personal "year in review" page you could click through, shamelessly similar to Spotify's year in review (I have't seen it in recent years so I think they stopped doing it).
For "most popular comment" surprise, surprise, it was the comment I deleted, there in full text.
After this I started using the method described above: editing every comment I make, saving a blank string, and then deleting. I usually do this once a week. It's tedious, but at least I can reasonably assume my comments are actually deleted.