How to remove a document type from the "New document" dialog in Sanity Studio

Perfect! You can hide the "Site settings" document type from the "New document" dialog using the newDocumentOptions configuration in your Sanity config. This is exactly what you need for singleton documents that should only exist once.

In your sanity.config.ts (or .js) file, add the newDocumentOptions configuration:

import {defineConfig} from 'sanity'

export default defineConfig({
  // ... your other config
  document: {
    newDocumentOptions: (prev, {creationContext}) => {
      // Filter out 'siteSettings' from the new document menu
      return prev.filter((templateItem) => templateItem.templateId !== 'siteSettings')
    },
  },
})

If your document type has a different ID than the template ID, you can also check the schemaType:

document: {
  newDocumentOptions: (prev, {creationContext}) => {
    const {schemaType} = creationContext
    
    // Hide from the global "New document" menu
    if (schemaType === 'siteSettings') {
      return []
    }
    
    return prev
  },
}

This approach is particularly useful for singleton documents (like site settings, global config, etc.) where you only want one instance to exist. The document can still be accessed and edited through the Studio structure - it just won't appear in the "New document" creation dialog, preventing your teammates from accidentally creating duplicates.

You can also combine this with the Structure Builder to provide direct access to your existing site settings document, making it easy to find and edit without cluttering the new document menu.