Remove author metadata from PDF annotations in preview?
I have the exact same problem. While you should anonymize yourself in the prefs, I don't fully trust that method, so:


Make a copy of the annotated PDF file
Drag and drop to open in a text editor like TextWrangler, or hex editor like  HexEdit
(Don't worry about any binary-looking weird characters)
Search for your name and replace with the exact same number of Xs or I usually throw in a space among the Xs so it looks like a different name.
Save the file in place
Open in Preview and mouse over the annotations to see the anonymized version