The Activities module helps users track tasks, events, and calls, with each parameter having its own vital information like priority level, status, and due date. 
The tasks, events, and calls can either be stand-alone records or associated with tickets. Creating a task 
Every ticket will have a to-do list for the agents to perform before it can be marked as closed. Tasks are the to-do list that ensures that the actions associated with a ticket are done in a timely and orderly manner. 
There can also be stand-alone tasks. For example, a user can create a task to perform a routine security scan, conduct a training session for new employees, and so on, which is unrelated to a ticket.
For every task, the agents can set reminders, priority, due date, and more to stay on top of the project.
To edit  or delete
 or delete  a task, click on the respective icons.
 a task, click on the respective icons.   Creating an event
Events are calendared activities. It helps agents schedule an activity that has a specific place, time, and duration so that they can keep better track of their programs and schedules. 
Individual events can also be created. For example, if a manager wants to set a reminder for the monthly review meeting, an event can be created to notify the team members about it, without having to create a ticket.
Users can edit 

 or delete  

 the created event. 
Making calls
Calls help users keep track of inbound and outbound calls in Zoho Desk. In the mobile app, users can also schedule calls so that the app pops up a reminder when it's time to dial in.

The users cannot make calls using the mobile app; they can only record the details of inbound and outbound calls and schedule calls. 
Users can edit 

 or delete  

 the created call.
Activity views
System-defined standard views categorize the activities as tasks, events, and calls.
In the activities view, the users can star or unstar views through the edit views screen, as well as reorder the views from the Edit Views screen.