Here is a sanitizer script that uses nothing but javascript

https://github.com/ryanford/Reddit-History-Sanitizer/blob/master/RedditHistorySanitizer.js

Open a tab, login to your account and go to your account page aka reddit.com/u/usernamehere (you likely need old.reddit version of your account, its all I use). Install tampermonkey and the script into that… It will iterate through your comments, overwrite them, then delete and refresh the page as it goes.

Change the line here:

const age = 7

to

const age = -1

To delete all comments. You can adjust that number (in days) to how old you it to filter for comments.