You could add Holidays to your Freshdesk Business Calendar or remove specific dates from the Holiday Calendar.

Set Holidays:

Yearly holiday list can be configured by adding specific dates to the holiday calendar. This could be done from under Admin > Team > Business Hours > Edit > Holidays, where you can add a date to your holiday calendar.

Change calendar holidays:

Kindly navigate to Admin > Team > Business Hours > Edit > and under the Holidays section, you could remove a specific Holiday from the list.