With the coming Reddit API changes in a couple of days (1st of July) scripts that purge comment histories may or may not work anymore. Thus this might be the last chance to purge your history. Not entirely sure but I've been planning to do this anyway.

I'm currently running this fork of Power Delete Suite: https://github.com/pkolyvas/PowerDeleteSuite

So far it seems to work fine. However it takes a long time (several hours depending on your history size) due to rate limits.

If you want to do so too:

• Go to the github page.
• Click the button at the bottom.
• Drag the button on the new page into your bookmark bar (not the address bar). On Brave you can enable or disable the bookmark bar in the appearance section of the settings.
• Go to your Reddit user profile (AFAIK you have to be logged in) and click the script button in your bookmark bar.
• If you want to edit your comments before deleting them (allegedly "deleting" only hides them) check the edit option. The dev recommends not to edit them to anything that could trigger auto-mods.
• Select filters if you want to exclude subreddits, etc.
• Click process and be prepared to wait. AFAIK you have to keep the browser window open.