Wentzel signed a new two-year deal with the club five months ago, and he was committed to them for next season despite Leeds' relegation from the Aviva Premiership.
But, after talks between the second-row forward and Leeds chief executive Gary Hetherington, Wentzel's contract will be terminated so he can pursue other options.
Hetherington said: "Unfortunately, following relegation, we have had to make some tough decisions about the club to enable us to build a squad that is capable of challenging to return to the Aviva Premiership at the earliest possible opportunity.
"We wish Marco all the best for the future."
Wentzel, 32, added: "Having spoken with Gary Hetherington, I understand the position that the club is in.
"While it is still a tough decision to leave the club, I hope they can achieve their goals for next season.
"The club faces some financial challenges for next season, and if by me leaving they are able to attract two or three players to strengthen the squad, I understand their position.
"I have spoken to a number of clubs, but I have not made any decisions as yet."
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