A simple note is basically an appointment without an attached patient record. You can use it in many ways, for example, to block a specific user time slot for booking, or assign a generic task for that particular date & time.
You can create a template for notes
To create a note, drag and drop on the empty calendar cell, then switch from the Appointment into the Note tab.
You can use the same notes templates as in appointments
Click on the calendar note to delete it, in the opened window confirm or cancel deletion