I have been helping one of the companies I work for make changes to their site. For the past couple of months I have been able to get rid of a sold-out badge. I have contacted the original theme developer as well as the company that altered the theme for our client. Could someone please help me find where I need to make the changes to get rid of the button. None of the default Shopify options work to change it. The store is https://www.thimblesquilts.com/ If you navigate to sewing machines and then Bernina seeing machines you can see sold-out products.
You should be able to disable the sold-out badge from within your theme editor. From your theme editor (Admin > Online Store > Themes > Customize) you will want to click on the dropdown box at the top of the editor that says 'Homepage' and select 'Collection pages'. From there you will see a 'Collection Pages' on the sidebar that you can click on which will show a variety of different options you can edit. In that left sidebar, you will see 'Theme Settings'. Click on that and from there your theme should have an option to disable the 'Show sold out badge'.
Let me know if this helps! If there is anything else I can help you with, please let me know.
Those are all plausible scenarios @Anttix! Your best bet would be to connect with your client's developer to get a better understanding of their changes or reach out to the developers of the Envy theme here to get a better understanding of any version history changes to their theme that would cause your existing version of their theme to not have that theme setting.
If there is anything else I can help you with, please let me know.