@echo off
for /f "usebackq" %%i in (`powershell -c "([datetime](get-date)).AddDays(-30).tostring('yyyyMMdd')"`) do set now=%%i

for /f "tokens=1-5* skip=4 delims=/ " %%i in ('dir /tc /od /a-d') do (
if %%i%%j%%k gtr %now% goto:eof
if "%%n" neq "" echo delete --- %%n
)