I made a phone call. How do I delete it from a list?

Every datum is important, therefore you should not delete any records from the system. Completed events and tasks should have the status held (for events) and completed (for tasks). After a while we tend to forget all Activities, referring to a certain Account or Opportunity. That is why the Activity's history is very useful.

After clicking the Save button a new window opens.

Select other Activity or click the No button.