Despite the 29-year-old spending most of last season out injured, Carlton has still made nearly 50 appearances since joining in 2011, scoring nine goals in the process.
However, much to the disappointment of the Shrimps boss, club finances have forced his hand as he prepares his squad for the coming season.
"The worst part of being a manager is that you have to make some really tough decisions and I'm really sad that we can't offer Danny anything," Bentley told the club's official website.
"He's worked really hard in the summer and looks in great shape and I would have liked to have kept him but the money is just not there.
"I'm really sorry to see him go because he is a big part of the club and I really do wish him well."