He removed the transaction after waiting couple of days. The tx was unconfirmed for couple of days on his old wallet version, later he updated the wallet but still it was unconfirmed. Then he managed to remove the tx.
Was it because of wallet version, he was in a wrong chain? If that was the case, I think in the updated wallet, the transaction would not be visible.
I got all the above point but still that does not fit the answer.