Thanks ... Found the answer myself ..
In case anyone is interested, from 'Help'
Remove holidays for a country from my Calendar
Click Calendar .
On the View menu, point to Current View, and then click Events.
Select the holidays you want to remove. For information about selecting multiple items, click .
Click Delete .
Tip To quickly remove all of the holidays for a country, click the Location column heading to sort the list of events to display all of the holidays for a country together.