SHOW MARKERS ONLY
For charts where displaying a series as a line, you have the option to show the line values and/or simply show the markers without the line. If you wish to show only the markers for all lines in your chart, to the Format Chart Task Pane, and in the General tab, click the checkbox Show Line Values. If you want to display the values only, and not the line, go to the Misc section, and check the checkbox Line Markers Only.
If you wish to show markers for only one line(s) in the chart, you can double click the line and in the Format Segment task pane check the Use Markers Only checkbox.