A quick and easy way to rename Windows directories is to use the LAUNCH EXTERNAL PROCESS command.
The following code demonstrates how to rename "MyOldFolder" located on drive D:\ to "MyNewFolder".

C_TEXT($source;$target) $source:="MyOldFolder" $target:="MyNewFolder"   `Hide the Command prompt SET ENVIRONMENT VARIABLE("_4D_OPTION_HIDE_CONSOLE";"TRUE")   `Set the drive where the external process is going to be launched SET ENVIRONMENT VARIABLE("_4D_OPTION_CURRENT_DIRECTORY";"D:\\")   `Launch the process to rename the file LAUNCH EXTERNAL PROCESS("cmd.exe /C ren "+$source+" "+$target)

The string "cmd.exe /C ren" starts the Command prompt , executes the ren command and closes it.
The syntax of the ren command is:

ren [drive:][path]source_file/directory target_file/directory