Deactivate usbhid on Odroid Xu4 with Legacy 3.10.104 debian jessie

Hello,

i am using an Odroid Xu4 in an open Access environment and i want to disable USB Keyboards. I already tried the following:

Create a file called, e.g., usbhid.conf in /etc/modprobe.d/ and add the following line:

blacklist usbhid
Then re-generate your initramfs with:

update-initramfs -u -k $(uname -r)
or, if you want to rebuild the initramfs for all installed kernel versions:

update-initramfs -u -k all
After you reboot, usbhid.ko will be prevented from loading. 

But it doesn't work for me. I Also get an Error while trying to update initramfs

dirtydroid@odroidxu4:~$ sudo update-initramfs -u -k all
ln: failed to create hard link ‘/boot/initrd.img-3.10.104-odroidxu4.dpkg-bak’ => ‘/boot/initrd.img-3.10.104-odroidxu4’: Operation not permitted
update-initramfs: Generating /boot/initrd.img-3.10.104-odroidxu4
/boot/initrd.img-3.10.103-odroidxu4 does not exist. Cannot update.

After this was failing. I tried to remove the usbhid from the drivers.

sudo rm /lib/modules/<your_kernel>/kernel/drivers/hid/usbhid/

But i don't find the usbhid anyhwere. Can u tell me which drivers I have to remove to disable usb keyboards? Or do u have any other suggestion how to ensure that no keyboards can be attached to the usb ports?

I really appreciate any help u can provide.