Another thing that requires XML-RPC to be active is the WordPress mobile apps, though I think these apps may also require Jetpack these days?
If you’re not using this, it’s fine to delete or disable it. We’ll be making this possible in ClassicPress v2 (petition, roadmap).
I wouldn’t be too concerned about the error in the search console - many millions of sites will be showing the same behavior, so it is not something that Google could reasonably penalize you for.