During the startup, those other planes are AI Aircraft that are being loaded.
As for your problem, it looks as if there is some issue that keeps spawning the X-15 Drop aircraft situation.
To try and troubleshoot this, go into the main X-Plane folder, then the Output folder. There, there should be a Preferences folder. Open this folder, and copy all of the files to a New Folder on the desktop (this will be a backup, if necessary, while also not interfering with the X-Plane process).
Now delete the files in the Preferences folder. Restart X-Plane, and it will be set back to default settings, which should include getting rid of this aircraft and situations assignment. Then, in-game, manually set back the rest of the settings you had.