Here's the trick I've found out for UNseasoning castiron. Put it in a campfire. Right in there, and get it glowing hot. I'll probably keep my weber kettle, just to un-season my 15 inch Lodge frying pan.
You can also put it in your oven, if your oven has a self-cleaning cycle.
3, 12 inch Lodge, and a 15 inch one. (I should get a griddle, because I only use the big one for pancakes.)
steve