In the System Monitor details pane, click the name of the counter in the legend.
To open Performance, click Start, click Control Panel, click Performance and Maintenance, click Administrative Tools, and then double-click Performance.
You can also delete counters by using the Remove button on the Data tab in the System Monitor Properties dialog box.
To delete all counters, click the button on the toolbar.
To clear all data samples from the display, click the button. (This button is available only when working with current data, not with log data.)
Change counters and counter properties
Quick reference to System Monitor settings
Add counters to System Monitor