Whitton, who was a close season signing from amateur club Siddal, leaves The Shay without making a single competitive appearance, with his sole outing in Fax colours coming in the pre-season game against Salford Red Devils in January.
Head coach Simon Grix said: “Liam requested a release on the grounds that he knew he was down the order with us and is just desperate to play regularly, which we don’t feel he is ready for here.
"It’s very disappointing as Liam has trained well and obviously has talent. It’s a shame as Liam knew he would need to be patient but the lure of weekly rugby in a familiar environment at Siddal was too much.
“It doesn’t really effect us at all as Liam was on a longer term development plan. I stand by my opinion that he has the talent to play at our level but it just wasn’t going to happen over night.
"We wish Liam all the best and at the end of the day, he is doing what he feels will make him happy and there are certainly no hard feelings from us.”