There are multiple ways to delete an item. First, go to the folders tree view and select the folder where the item is located. All the items for this folder will be displayed on list situated on the right side of the folders tree.

Then you can do the following:
1. Right click on the item that you want to delete and choose the Delete option from the displayed popup menu.

or,

2. Click on the item that you want to delete and then click the Delete button on the toolbar (this is the fourth button on the toolbar)

or,

3. Click on the item that you want to delete and then go to File menu and choose the Delete Item option.

or,

4. Click on the item that you want to delete and then go to the corresponding menu (that is if you are in an item that contains alarms/contacts/events/notes/tasks, then you have to go to the Alarms/Contacts/Events/Notes/Tasks menu) and choose the Delete option.

The selected item will be deleted from the database.