Is it circumventing the Mylot guidelines if I rewrite some of my previous discussions?

It depends what you mean by 'rewrite'. As long as the new discussion is completely rewritten, you should be OK but, to be on the safe side, you should delete the old discussion before you post. (You need not worry about losing earnings, by the way, when you delete a discussion. Any earnings already recorded are not deducted when a discussion is deleted.) If you want to preserve the responses and comments you had on the original discussions, there is nothing to stop you saving them in an offline document for your personal use although you should remember that they are still legally the property of the person who posted them, so if you wanted to quote them, you should ask for the author's permission and give due attribution, even if they have been deleted.

I guess it would be circumvention for sure.

Kind of depends what you want? Do you want the topics you wrote before left intact or it doesn't matter. If you want to delete the posts it is okay but if you want to reference them that is another thing I guess. I found comments on old posts became ... obsolete.

I have no idea because I wasn't even around here that long

Since I am new here I would be interested in reading some of your older discussions. I am not sure how it works but if you rewrote it then I can't see where the problem would be.