To do this, double-click the header, and then click the format pane to select the text (Figure 1).

According to you, there is another situation? There is a short line at the bottom of the page number.

The way to get rid of that short line is to double-click the title, click the page number and have a look (Figure 2).

Select the border (Figure 3); Remove the line on the red circle (Figure 4) and click OK.