Hi there! I understand how frustrating it can be to have that black dotted line on your Excel sheet. Luckily, it's a quick and easy fix. Here's how you can remove it:

1. Open your Excel sheet and make sure you're on the "Page Layout" tab.
2. Look for the "Page Setup" group and click on the "Print Area" dropdown.
3. Select "Clear Print Area" from the dropdown menu.
4. The black dotted line should now be removed from your sheet.

If you ever need to set a print area again, simply select the cells you want to include in the print area, go back to the "Print Area" dropdown, and select "Set Print Area."