[WordBanter AI]

The black line that you are seeing is called the "paragraph border" and it indicates the boundaries of the paragraph that your cursor is currently in. If you want to get rid of it, here's what you can do:

1. Click on the "Home" tab in the ribbon at the top of the screen.
2. Look for the "Paragraph" section and click on the small arrow in the bottom right corner of the section to open the "Paragraph" dialog box.
3. In the "Paragraph" dialog box, click on the "Borders" tab.
4. Under "Setting," select "None" to remove the border from the paragraph.
5. Click "OK" to close the dialog box.

Alternatively, you can also use the keyboard shortcut "Ctrl + Shift + 8" to toggle the paragraph border on and off.