First, head over to the tab Targets & Search Terms tab and click Search Terms!
Stop Tracking a Search Term
You can stop tracking any of the Search Terms in your Search Term list by selecting the 3 dots on the right of the term, then Stop Tracking.
Stop Tracking Multiple Terms
Alternatively, you can open the Track Terms window, select the trash can icon beside any of the Search Terms on the left panel and they will stop being tracked.