Basically guessing where you use that asset, like a level or a BP, then opening that and compiling/resaving it. If you have no idea where you use it then you could simply delete it (rather remove it from your project with Windows explorer so you can copy it back) and then restart your project which might give you better error messages where the asset is now missing.
You can try the “find in blueprint” feature or the reference viewer, it’s basically just pocking in the dark.
It’s a lengthy task sometimes you have to just try and save and hope the best, it sucks that there is no better way to finding thiose references.