Me, According to Google

If you’ve ever had a problem deleting a horizontal line in Microsoft Word,
this post is for you. The answer is something of a trick, as the horizontal
line is not a line (or a graphic), it’s a bottom border.

Removal

1. In Office 2013 go to the Design tab and look to the far right for the
   Page Borders button.

2. Within the borders settings, click on the leftmost tab titled Borders
   (not Page Border)

3. select the top left option of None.

That will delete the border (horizontal line) from the area in question.

…or…

1. Place the cursor immediately above the horizontal line.

2. On the Home tab in Word or the Format Text tab in Outlook, in the
   Paragraph group, click the arrow next to the Borders and Shading button

3. and click No Border.

Notes

1. In previous versions of Word the solution is similar, i.e. find the
   Borders and Shading option and delete that bottom border.