It’s impossible to remove all of the air in there, so remove what you feel is appropriate (I’d recommend at least, oh, 1 psi). Then you can honestly say you’ve deflated them.
What do “they” think’ll happen anyway ? I bet guess the atmospheric pressure drop at 30,000 feet is less than the internal gain when you even sit on the bike, let alone landing one of your massive jumps
(edit: actually I suspect the change on sitting on the thing is probably small but I still don’t think you need to deflate)
Personally, I do deflate but that’s determined by getting them to fit into my case – down to about 10psi I’d guess and I’ve never brought down a plane in the process