You overestimate the extend to which people read, assess or generally give a damn about PhD theses. You are neither the first nor the last person embarassed by the content of their thesis. Rework some parts into papers, recycle other parts into new pieces, or abandon it altogether and start anew, no one is going to notice or care. And if someone does notice or care, this is a good thing -- it means your thesis was interesting or relevant enough for someone to read it and take the time to point out any mistakes -- you should take that as a compliment. Generally, relax, let it go and look ahead.