That is an advanced customization,
- first check theme for any settings to disable certain filters or contexts
- reach out to the themes developers to make the feature request that filters that are binary(off/on , instock/outofstock ) either only show 1 state at a time or behave like a toggle.
- hire someone for the customization after reading and understanding the below User Experience warning to be sure it fits the context of the themes design:
Just because a road is closed doesn't mean you have to remove the asphalt , at some point people need to still know what the possible path is BEFORE they need it.
Though yes if such a thing is unusable the argument is only available options should be viewable and unavailable options it shouldn't be seen at all .
Deleting/hiding an option may be against the themes design intent of informational permanency overview awareness versus removing|truncating information; you don't want to keep customers unaware of options they may be able to change too regardless if the current set of filters means that option isn't usable (note how I do not say the option is irrelevant).
Irrelevant options would be say a gender filter when the entire collection is women, or color for a collection of products that only ever come in 1 color.
The other thing displaying disabled choices can do is help highlight options that are selected by contrast; when not using things like checkbox toggles.
