Can I Delete Library Containers Mac

A lot of Mac tutorials mention the Library folder, which is where your macOS applications store things like settings and caches. Some settings can only be changed by editing files in the Library. But the Library is hidden by default.

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You can remove an add-in that you've previously sideloaded on Windows, Mac, or iOS by clearing the Office cache on your computer.

It's not a standard Folder, I would suggest you to switch on invisible files to see if something resides there, if not delete the Folder. The only App I remember using the word Container is.
And Apple software updates can reinstall ones you've deleted so it's not necessarily a one-time removal routine. I don't see any reason to risk removing those files unless reclaiming disk space is a necessity and there are no safer alternatives.

Additionally, if you make changes to your add-in's manifest (for example, update file names of icons or text of add-in commands), you should clear the Office cache and then re-sideload the add-in using updated manifest. Doing so will allow Office to render the add-in as it's described by the updated manifest.

Clear the Office cache on Windows

To remove all sideloaded add-ins from Excel, Word, and PowerPoint, delete the contents of the folder:

If the following folder exists, delete its contents too:

To remove a sideloaded add-in from Outlook, use the steps outlined in Sideload Outlook add-ins for testing to find the add-in in the Custom add-ins section of the dialog box that lists your installed add-ins. Choose the ellipsis (...) for the add-in and then choose Remove to remove that specific add-in. If this add-in removal doesn't work, then delete the contents of the Wef folder as noted previously for Excel, Word, and PowerPoint.

Additionally, to clear the Office cache on Windows 10 when the add-in is running in Microsoft Edge, you can use the Microsoft Edge DevTools.

Tip

If you only want the sideloaded add-in to reflect recent changes to its HTML or JavaScript source files, you shouldn't need to clear the cache. Instead, just put focus in the add-in's task pane (by clicking anywhere within the task pane) and then press F5 to reload the add-in.

Note

To clear the Office cache using the following steps, your add-in must have a task pane. If your add-in is a UI-less add-in -- for example, one that uses the on-send feature -- you'll need to add a task pane to your add-in that uses the same domain for SourceLocation, before you can use the following steps to clear the cache.

Install the Microsoft Edge DevTools.
Open your add-in in the Office client.
Run the Microsoft Edge DevTools.
In the Microsoft Edge DevTools, open the Local tab. Your add-in will be listed by its name.
Select the add-in name to attach the debugger to your add-in. A new Microsoft Edge DevTools window will open when the debugger attaches to your add-in.
On the Network tab of the new window, select the Clear cache button.
If completing these steps doesn't produce the desired result, you can also select the Always refresh from server button.

Clear the Office cache on Mac

Add-ins are often cached in Office for Mac, for performance reasons. Normally, the cache is cleared by reloading the add-in. If more than one add-in exists in the same document, the process of automatically clearing the cache on reload might not be reliable.

You can clear the cache by using the personality menu of any task pane add-in.

Choose the personality menu. Then choose Clear Web Cache.
Note
You must run macOS version 10.13.6 or later to see the personality menu.