Finding all directories within a directory recursively:
dir /a:d /s /b <dirname pattern>
dir /a:d /s /b tmpdir*
the /a:d flag restricts the results to directories, /s does a recursive search and /b prints the results in bare format.
Why bare format? Because that makes it suitable as input to the FOR /F command. Putting them together, you can delete all these directories with:
FOR /F “delims=” %i IN (‘dir /a:d /s /b tmpdir*’) DO rd /s /q “%i”
FOR’s /F allows, among other things, using the output of a command (in between the single quoted parentheses) as input to a command that’s repeated (the part after the DO). In this case we’re executing RD (remove directory) on each directory that starts with the name tmpdir.