I used Power Delete Suite the other day. It takes a while to run because it's scripted vs using API. Instructions were simple and easy to use. Just let it run in a tab in the background and eventually it will work through all your posts or comments. I set it to just edit all my comments. If you leave the text box empty for what you want it edited to it will put random comments in, such as I like coffee. I like hiking. I like reading. I like beer. Etc.