This is for windows  - type on the command line to list all node_modules folders:
For /d /r . %d in (node_modules) Do @IF EXIST "%d" echo %d

To delete all the listed folders:
For /d /r . %d in (node_modules) Do @IF EXIST "%d" del /Q "%d"

The /Q flag is "Quiet mode" - Does not ask if ok to delete on global wildcard