I disabled storage USBs on an xubuntu 14.04 machine as Administrator user called admin by:

mv /lib/modules/$(uname -r)/kernel/drivers/usb/storage/usb-storage.ko /home/admin/

In /etc/rc.local add:

rmmod uas
rmmod usb_storage

Reboot. Now ordinary Desktop users should have no way to connect USB storage devices. This can be useful e.g. eliminate risk of data exfiltration or malware propagation via USB storage devices. Pity there is no user group to control this.