Whitton lets youngster go
The 19-year-old defender joined fellow youngsters Triston Chambers and Glenn Williamson in signing short-terms professional contracts this summer at Layer Road.
However, Whitton has decided to let the speedy wing-back go once his three-month deal expires after he was failed to break into The U's first team, having made only one substitute appearance last season for the club.
On the decision to release Hadrava, Whitton told the Colchester United official website: "The time has come for David to find first team football and get his career started, and we felt that we were only holding him back by keeping him at Colchester United.
"It seemed unfair to keep David at the club as we were unlikely to use him with the other players we've currently got.
"The challenge for David now is to go out there and find first team (football) and find his level in the game.
"He's a great kid with a great attitude and we wish him all the best in the future.
"We'll be doing everything we can as a club to help him secure a contract somewhere else."
Meanwhile, former Colchester target Ruel Fox has revealed that he has not joined non-league Stanway Rovers, despite initial reports last week.
The veteran midfielder also stated that he had not turn down an offer from the Layer Road club to join Stanway, despite Colchester making an enquiry about his availability.
The former Norwich City, Newcastle United and West Bromwich Albion player, who has been doing some coaching at Division Three side Southend United, refuted claims that he was headed to non-league football.
Fox said: "I'm in the lucky position where I don't really have to play again.
"I'm comfortable financially and just deciding what to do next.
"I don't know where this story came from but it's got a bit out of hand.
"With all due respect to Stanway, I don't want to play at that level and get kicked around.
"I hope this sets the record straight. I've just met up with my old friend (Stanway Rovers manager) Steve Ball.
"People shouldn't expect me to turn up for the next Stanway game."