You can open this page by clicking the Side Menu->Admin->Event Type.

This page allows you to edit your list of customised event types. For each section (Vacancy, Candidate, Client, Contact), you can add 10 user-defined events. These are used when you add an event from a section, for example, a Candidate or a Contact could have events “Phone Call” or “Sent Terms” or “On Holiday”, and so on.
WARNING – Once you setup the event types and these are in use, it is not recommended to change the meaning of existing event types (except spelling or wording) because these entries are used as a cross-reference against all the event lists.
You can select the object, then add the required event, and click Save to update the record.