How to turn off shared airfields

I shared a map with a player. The next thing I know he is planning on moving the entire army right down the middle of my territory. After some discussion going nowhere, I turned of shared map and replaced with peace. I still see his strategic bombers now flying and enroute to one of several of my airfields they will use before going to trucks for the remaining distance.

How can I stop him from "sharing" my airfield. He may have p[lanned this while the maps were still shared. Does this mean it is a one way trip? In other words, he can not plan a return journey through the same airfields because I am no longer sharing a map?

It seems to me that trucks don't capture territory. Can confirm that his truck will pass without capturing territory?

Thanks in advance.

Sluggo