The Jamaica captain was trialling with Pompey, but has now been sent back to Sporting Kansas City.
"Shavar has gone back," Pompey boss Steve Cotterill told The News.
"He did well in the game the other night but I don't think he would be anything better than what we already have at the football club.
"He's a really nice lad but we've got some nice lads and good players as it is.
"We didn't want another in there if he wasn't better than what we already have."