How to delete the comment in the pdf?

I wasn't able to try your example, because it was using a non-standard font that would have required me to download a font pack.

In general, to delete a comment in Adobe Reader, you simply right-click on the comment you want to delete, and select "Delete" in the menu that pops up.

Comments never come back when I delete them that way. If your comments continue to return, then it sounds like there's something wrong with your document.