Linux Disk Space – Fixing ‘No Space Left on Device’ Error

I'm getting following error while doing tab, tab inside of shell:

-bash: cannot create temp file for here-document: No space left on device

root@alexus:~# cat /etc/issue.net
Ubuntu 14.04.3 LTS
root@alexus:~# uname -a
Linux alexus 3.13.0-57-generic #95-Ubuntu SMP Fri Jun 19 09:28:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
root@alexus:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        30G   17G   11G  61% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            487M  4.0K  487M   1% /dev
tmpfs           100M  404K  100M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            498M  352K  497M   1% /run/shm
none            100M     0  100M   0% /run/user
root@alexus:~# df -i
Filesystem      Inodes   IUsed  IFree IUse% Mounted on
/dev/vda1      1966080 1966080      0  100% /
none            127234      11 127223    1% /sys/fs/cgroup
udev            124520     402 124118    1% /dev
tmpfs           127234     346 126888    1% /run
none            127234       1 127233    1% /run/lock
none            127234      19 127215    1% /run/shm
none            127234       2 127232    1% /run/user
root@alexus:~# 

how do I free inodes?