code: public boolean delete(@NonNull Document document, @NonNull ConcurrencyControl concurrencyControl)
          throws CouchbaseLiteException {
          if (document == null) { throw new IllegalArgumentException("document cannot be null."); }
          if (concurrencyControl == null) { throw new IllegalArgumentException("concurrencyControl cannot be null."); }
  
          // NOTE: synchronized in save(Document, boolean) method
          return save(document, true, concurrencyControl);
      }
docs: Deletes a document from the database. When used with lastWriteWins concurrency
  control, the last write operation will win if there is a conflict.
  When used with FAIL_ON_CONFLICT concurrency control, delete will fail with
  'false' value returned.
  
  @param document           The document.
  @param concurrencyControl The concurrency control.
  @throws CouchbaseLiteException