Getting rid of an offensive airport

for some reason i have an offensive airbase from my main country, inside one of my slave countries and i cant get rid of the base. can someone explain how i get rid of it? its not showing up in my remote deopots so i can just close it. main country is the kingdom of gracemeria and the slave is the independent state of somati.

these countries reside in FB

Your last offensive military base and airport cannot be destroyed.

Sometimes a base, or any other map item is painted outside your country.
Functionally it behaves as if it is in the country.

This has nothing to do with the possibility to remove a military base.

You can move any item painted outside your country to another location.
you can remove military bases of all types, except for the last one (as Johanas already explained).

We intend to enhance the use of military bases but the last base will not disappear.
It can be damaged to 99% and will not really function, but it will not disappear.