This site is being deprecated.
Please see the official X‑Plane Support page for help.
It sounds like the file has gotten set to be read only. We do not recommend installing X-Plane to C: or to Program Files (unless you're using Steam) because it can cause permissions issues later on.
See this article for more info on these locations & how to fix them.
As a last ditch method you can delete the problem files.
This site is no longer being actively maintained.