If you are using you have to add a link to a document or page or Image. there is no out of the box to remove it.
Instead of using Hero webpart, you can use Image Gallery webpart in SharePoint Online. But you will not get the exact look and feel as of Hero webpart.
In Image gallery webpart, you will get 3 different layouts:
Also, you can choose to show the static/selected images or you can dynamically display images from a document library.
Microsoft official documentation: Use the Image Gallery web part
If you want the exact look and feel then you have to develop the custom webpart using SharePoint Framework.