In S Planner you can hide them: S Planner -> Calendars -> Display -> Uncheck Contact's birthdays. However, this option if not found in Standalone Calendar.
With Birthday Adapter installed your calendars "Contacts birthdays" have to be hidden, otherwise duplicates of birthdays are being displayed; Unfortunately Standalone Calendar do not have this option.
Contact birthdays are showed automatically.
In S Planner you can hide them: S Planner -> Calendars -> Display -> Uncheck Contact's birthdays. However, this option if not found in Standalone Calendar.
Can you please add it?