First, work with a copy of your document. Remember that UnDo is your friend.

You can find and replace styles. Figure out which style is applied to one of the bogus entries and replace the style setting with what you are using for your body text. This will catch some legitimate headings as well. You'll need to reapply your heading styles to those. Remember the keyboard shortcuts for headings 1-3.

Replace = Ctrl+H
Click on the More button then Formatting > Styles. Do this for the Find box and the Replace box with no text in either.