FYI, I’ve modified the title of this topic to reflect this wish is for Free Flight.
There is a specific wish for this request in career mode that the community may be interested in:
@MathieuSK: That wish was created by you back in November. If you like, I can merge this wish into that one, combine the votes, and modify that title from “Disable ATC in Career Mode or Option to Disable” to “Provide Option to Disable ATC in Career Mode and Free Flight”.