A recurring injury means that the Australian-born forward cannot take part in the Bulls’ preseason programme.
The club do, however, retain his registration, should he be able to prove his fitness at a later date.
“Mark has only been able to play a couple of games since he returned to Australia earlier this year,” said Bulls managing director Steve Ferres.
“He has contacted us, making us aware of his situation and we have agreed to release him from his contract.
“Obviously this frees up spots on our overseas quote and non-federation trained lists, meaning we now have an option to bring someone else in.
“However, we are in no rush to do so – with five front-row forwards on board for 2015.
“Pre-season training is now well underway and Jimmy (Lowes) will now assess his troops, before making a judgement on whether a further addition needs to be sought.
“Heading into the winter months with space on the quota leaves us in a strong and healthy position, with the rest of our squad getting stuck into pre-season training.”