Warning: This may disable other memory card readers.
Open terminal and enter the following command
lsmod | grep tifm
Now You need to edit the blacklist file using the following command
sudo vi /etc/modprobe.d/blacklist
At the end of the file, enter each module listed on the lsmod output one at a time with "blacklist" proceeding it. Here's mine:
# Disable Memory Stick
Save the file and exit,Now you need to reboot your system