This task can be solved by different ways.
Here is a proposal, which moves only the media files, and will leave alone other files.
Convert "Tag-Filename"
Formatstring: $replace(%_folderpath%'$',%_directory%'$',%artist%''%_directory%)''%_filename%
Here is a proposal, which will create a new folder, which is one level above the folder containing the tracks.
Convert "Tag-Tag"
Field: _DIRECTORY
Formatstring: %_folderpath%'..'%artist%''%_directory%
See also ...
/t/10728/1
/t/16957/1
DD.20171007.1030.CEST