SHELL

batch delete all files in subfolders of type

del /S *.jpg

del - del command is used delete files from a computer
/S - recurses subdirectories and checks their contents
* - wildcard for the filename
.jpg - the type (extension) wanted

batch delete all folders and files

for /F "delims=" %%i in ('dir /b') do (rmdir "%%i" /s/q || del "%%i" /s/q)