Hi young,
Thanks for your post, and especially for including that link so I could check this out. That Add Events button links to the default url for our Community Events plugin’s Add Event page. But I see that you do not have a license for Community Events.
I did notice, however, that The Events Calendar is built into your theme and that your theme was recently updated. The theme says that it is compatible with Community Events, so it’s possible that the last theme update added those buttons. In that case, they would be giving you 404s because you don’t have the corresponding pages that they link to.
The other possibility is that someone else is working on your site and added those buttons to the sidebar, but that seems less likely.
I recommend that you check out your Widgets page and see if there is a new widget that adds those buttons. If so, you can simply delete it. If there isn’t a widget there, you should email your theme’s developer and ask about this. They can probably point you towards how to remove the buttons.
Please let me know if the above helps and if there’s anything else I can do for you.
Best,
Leah