Freeing space on AWS EC2

Environment

AWS instance EC2: t2.micro
OS: Linux Ubuntu 16.04.2 LTS

Noticing my server was excessively slow I logged in through ssh in the terminal.

After trying to execute a simple cd command I got the following error message:

No space left on device

I run the following command in order to display the biggest folders:

puts 'du -a / | sort -n -r | head -n 20'

Result:

4631892 /usr
3376452 /usr/src
1306868 /lib
1216332 /lib/modules
896280  /var
661540  /boot
548124  /var/lib
434396  /usr/bin
384996  /usr/lib
247080  /var/lib/mysql
230360  /usr/share
208144  /var/www
208140  /var/www/html
183928  /var/www/html/wp-content
150876  /var/lib/apt
150820  /var/lib/apt/lists
143004  /usr/local
129688  /usr/lib/x86_64-linux-gnu
126616  /var/lib/dpkg

After checking the /usr/src folder I noticed the following files were taking a huge place:

linux-headers-4.4.023    
linux-headers-4.4.023-generic    
linux-headers-4.4.026    
linux-headers-4.4.026-generic
linux-headers-4.4.029    
linux-headers-4.4.029-generic
linux-headers-4.4.031    
linux-headers-4.4.031-generic    
linux-headers-4.4.032    
linux-headers-4.4.032-generic    
linux-headers-4.4.033    
linux-headers-4.4.033-generic    
linux-headers-4.4.034    
linux-headers-4.4.034-generic    
linux-headers-4.4.035    
linux-headers-4.4.035-generic    
linux-headers-4.4.036    
linux-headers-4.4.036-generic     
linux-headers-4.4.037     
linux-headers-4.4.037-generic

Those files being old linux headers files I decided to purge them with

sudo apt-get autoremove

Allowed me to free about 30 Mb of memory. It seems very little but on t2.micro it has a significant impact.