When playing a mission with hostile administrators the player has the option to try and take over their sections.
See also: Combat
To do this you must have a security scuzzer present and click on a bulkhead door, if the takeover symbol is available then pressing it will summon the scuzzer to hack the door lock. After that its just a matter of doing the same on the next door across. Your enemies will try and stop this however, so best bring lots of security forces to help defend the scuzzer while they are working. Muster points (Click and hold right mouse button) can be used to assemble you combat ready peeps and Security scuzzers.
If you take over all their sub level sections with power collectors then you will remove that administrator from the station, allowing you to claim the rest of their territory without your scuzzers help.
Take steps to protect your own bulkhead doors from a similar fate by placing Security Columns along the route to the door control.
Sometime neighbouring administrators don't want to fight. Using the peep control panel, overview section, you can provoke them into combat, allowing you to seize their sections. You can do this by click on their icons, which display the percentage they are friends/foes with you. Provoking them will allow you to attack their sections and for them to attack you.