Get a Harbor Freight weed burner and just burn out the liner. You do it from the outside until it turns black and then back pink. Then pressure wash it out. Takes about 1-1/2 hour start to finish.. Trust me. I have done 6 of them in the last 2 months.
Incidentally, it will take a full tank of propane to get it done.
XL BGE, Cold smokehouse, Kamado Joe Jr, Santa Maria pit, Backwoods Chubby, 26.75" Weber custom performer, Blackstone 36" griddle, MAK One Star pellet cooker, 22"WSM, Jumbo Joe, WGA, Smokey Joe
Custom wooden handles for BBQ's made by Marty Leach (oh, that's me)