"We take matters of player conduct extremely seriously and have been happy with the professionalism and discipline of this squad in general terms," said Wales team manager Alan Phillips.
"Andy knows he has misbehaved and is apologetic, but he also knows that he must take responsibility for his own actions and accept the repercussions.
"This kind of behaviour cannot be tolerated in a professional, elite sporting environment and we have acted quickly and incisively in order to leave no ambiguity over the dim view we take of this situation.
"The player has made his private apologies to the Welsh management team as well as apologising in a public statement and we have also asked him to apologise to the Vale Resort Hotel, before asking him to leave the squad.
"We will now leave the South Wales Police service to conclude the matter and we will be making no further public statements at this time."
A specific replacement for Powell will not be added to the Wales squad, although the inclusion of Scarlets hooker Ken Owens as cover for his injured regional colleague Matthew Rees (groin) and Blues hooker Gareth Williams (knee) means the squad retains 35 members.