code: public void retractObject(final InternalFactHandle handle,
                                final PropagationContext context,
                                final ObjectTypeConf objectTypeConf,
                                final InternalWorkingMemory workingMemory) {
          if ( log.isTraceEnabled() ) {
              log.trace( "Delete {}", handle.toString()  );
          }
  
          workingMemory.addPropagation(new PropagationEntry.Delete(this, handle, context, objectTypeConf));
      }
docs: Retract a fact object from this <code>RuleBase</code> and the specified
  <code>WorkingMemory</code>.
  
  @param handle
  The handle of the fact to retract.
  @param workingMemory
  The working memory session.