[Georgio]

Код:

@echo off

setlocal

set "folder=C:\ftp\rpo"
set "number=7"

pushd "%folder%"
for /f "delims=" %%i in ('2^>nul dir/a-d/b') do (
 set name=%%~ni
 2>nul cmd/v/c ren "%%i" "!name:~%number%!%%~xi"
)
popd

endlocal