The trend line is fitted with scattered points, so scattered points cannot be deleted. If you delete the scattered points, the trend will be gone. However, scattered points may not be displayed, as follows (refer to the attached figure):

1. Right-click any scatter point in the diagram to open the menu and select Format Data Series;

2. In the dialog box that appears, select "Data Marking Options";

3. Select "None" in the sub-option "Data Tag Type" of "Data Tag Options".