Either you're planning summer vacations or a winter break in your office, you may want to disable the callback option from the widget. You can do this globally for the entire company, or locally for specific users.
1 . Setting holidays for the entire company
Change your business hours within your company settings.
Settings > Company > Business Hours
Amend time and save.
2. Setting holidays for specific users
If some of your users are unavailable to answer calls for a few days, and you don't want the callbacks to be forwarded to them during that period, you can set personal holidays for each user. You can do this individual user settings:
Settings > Personal > Working Hours
Add dates and save.