@Vitold69 FS Traffic doesn't have a way of deleting an entire airline via a single button, but you can unassign liveries for aircraft types, and delete a certain aircraft type from an airline, via the Traffic Control Centre > Aircraft Manager > Liveries page.

For example, if you would like to remove all British Airways A380s from the schedules, you can simply delete the assigned livery on the Liveries page and no British Airways A380s will be generated in the simulation.

If you do this for every aircraft type in an airline, you will still see the airline's flights listed in the flight schedules, but they won't be generated in the simulator as they don't have any assigned liveries.

Hope that helps.

Mark - Just Flight