When using Lighting the Activities Sidebar can be customized to fit your needs. Tabs (e.g., New Task, New Event, Log a Call, and Email) can be added, removed and reordered. For Actions that will not be used, such as Email from Salesforce, the tab can be removed to eliminate confusion.
To manage Activities Sidebar Tabs:
- Open Set Up and then the Object Browser.
- Click on the object to customize. For this example we will use Event.
- Click on Page Layouts and then your current layout.
- Select Mobile & Lightning Actions from the list
- Scroll to the Mobile and Lightning Experience Actions Section
- Drag an action you want to add from the top section.
- Drag fields from the screen back to the top section to remove them.
- When done, click the Save button on the Action bar.
- View your changes in production.