Howdy,
I think that when they are referring to the library/calendars, they mean to say, on the USERS's library folder, sometimes written as ~/library.
*** Warning ***
YOU probably should not delete items from your calendar folder, this could be very very bad!!
*** Warning ***
To be really clear, this may not be a safe thing to do, you probably don't want to delete calendar data that may contain other calendars, or otherwise not be safe to do for various reasons... not the least of which is that it may not really fix anything anyways, and may also make things worse for you.
So, having said all that:
Well, one more time:
Nor may it even be fix the issue, as I'm not sure if this is actually working for folks more then temporarily, as some have reported that temporarily, unchecking the 'internet accounts' or deleting the 'internet accounts' for your google calendars, TEMPORARILY, only, seems to show your data, then, it disappears again, and it fail too.
So, if you want to understand what perhaps was meant for your understanding, and knowing that you probably should NOT do this, nor will it be likely to help fix anything, and it may very well make things worse or cause other problems, and you've backed up all your data also of course, and are sure it's a good backup you can safely recover files and data from, and are willing to take risks on non-recommended actions:
Well...
Then...
I think, what they meant was :
folder path:
hard disk drive (Macintosh HD or whatever it's named)/Users/YOURuserNAMEhere/Library/Calendars
However, sometimes the 'user' library folder is hidden in the finder, and you have to specifically jump to it, or reveal it, either with:
in finder, holding down the option key, click on 'go menu', select 'library' that now appears
or
in finder, go to your user home folder : Macintosh HD/Users/UserNameHere/
then, click on view menu, select 'show view options' , then check box for 'show library folder'.
Then, inside your USER's library folder, you can see the 'calendars' folder, but I'd really caution most folks against deleting all the data in there, as it may cause you problems.
As this is suddenly happening for many different folks, on many different Macintosh computers, it seems more likely the issue has nothing to do with any of this, but rather, Google perhaps made a change, and now the data won't sync with Apple's Calendar.app and there is probably nothing we can do other than report the issue to Google and wait for the issue to be fixed hopefully.
In the meantime, use a web browser, go to 'calendars.google.com', login with your Google account, and use your calendar that way for now, or like someone else suggested, BusyCal, or use your iPhone, iPad, or other devices and/or web browsers until this issue gets fixed for everyone.
Cheers,
Daniel