It was not easy to figure out how to unhilghight text in GoodReader.
After trying every item of context menu on selected text, long touch and swipe on Annotations list, I consulted the Google. I found a Question but that didn’t help me a lot.
It turned out that I just needed a single touch on the highlighted text. GoodReader finally showed me the context menu below.
That’s it. It jsut did what’s expected.