Dont save webform data to database
What files are you referring to? 

If there are files being generated from webform node content then the data probably has to be saved first in order to generate the files. In this case you should target to delete the nodes once the email has been sent (while allowing for them to be created at first). You can look into Rules module for that. 

Webforms all have separate email settings so I'd expect the webform_clear to also offer per-form settings.