Hi Alan,

Unfortunately you can't do that with the calendar built-in to Website X5.

However, there are numerous different freeware PHP calendars available on the web, which you could incorporate as part of a Website X5 project.  Some of these calendars allow you to edit dates/show dates as 'unavailable' etc.  -  it would be a case of following the instructions provided with each one.

If you do use a PHP calendar add-on, then remember to set the 'File Name Format' of the web page in which it's placed to .php (instead of .html)  -  see Page Properties in Step 2 - Sitemap Creation

https://support.google.com/calendar/answer/41207?hl=en