How can I change the hard disk name in Ubuntu?

You can use Labeling Program for Ubuntu.

but if you want something with Terminal, try this

for FAT 12 and 32 Systems, these file systems are most often found on USB thumb drives, flash cards (like for a camera or cell phone), and older external USB hard drives. but may be if your hard disc is FAT 12 or 32 . Thus, check current name in terminal

sudo mlabel -i <device> -s 

for example : sudo mlabel -i /dev/sdb1 ::my_external

if not you edit mtools.conf as sudo

sudo nano /etc/mtools.conf 

add something like for each drive:

   drive p: file="/dev/sdb1"
   drive q: file="/dev/sdb2"

Then use sudo mlabel p:new_label . for example , sudo mlabel p:30GB_FAT32

If your HD is in NTFS ,

first, check the current label sudo ntfslabel <device>

and rename like that sudo ntfslabel <device> <label> Note: 128 characters maximum.

most of linux formatted HD are with ext3, ext4 . thus,

check the lable first sudo e2label <device> and rename sudo e2label <device> <label>. Note: 16 characters maximum.

for more, you should take a look at here.

Show Applications -> Disks -> select disk to change name -> setting icon -> edit filesystem -> change -> done