gnatclean command has the form:
$ gnatclean switches names
names is a list of source file names. Suffixes
adb may be omitted. If a project file is specified using switch
names may be completely omitted.
In normal mode,
gnatclean delete the files produced by the compiler and,
-c is not specified, by the binder and
the linker. In informative-only mode, specified by switch
-n, the list of files that would have been deleted in
normal mode is listed, but no file is actually deleted.