Does tailless means no tail at all?
Tailless means no horizontal tail, but a vertical tail is still allowed. Examples are the Convair F-102 or Convair B-58.



Convair B-58 Hustler (picture source)

Compare this to a flying wing: Here even the vertical tail is left off. Since a classic delta would have too little lever arm for yaw control, this requires a higher aspect ratio wing. An example is the Horten IX:



Horten IX V1 prototype aircraft (picture source)