This has been plaguing me for years!

I write something in Word and then want to separate the text from the next body of text--so I run an equal sign (=) a few strokes, hit enter, and I get a neat ===== that goes from left to right margins. Great--so far. But when I try to remove that line later I find that simple task to be impossible. I have gone so far as to highlight all but the equal-sign line, copy, and then paste on a new Word document--all to no avail! The damn line is there too. IT WILL NOT DIE! Can ANYONE tell me how to delete it??