We've had discussions about front hub adapters for duals before. Usually it's just a one piece dual wheel type hub, no extension, and confusion as to how the drum is bolted on.
To remove the drum first remove hub from spindle and then unbolt drum.
Unless you do have actual hub extensions bolted into a standard single wheel hub? Then remove extension and then drum. This would be uncommon and I think aftermarket but not 100% sure, I've never seen any in person.
Have pictures?
