Ubuntu is a Debian-based Linux operating system, with Unity as its default desktop environment. It is based on free software and named after the Southern African philosophy of ubuntu (literally, "human-ness"), which often is translated as "humanity towards others" or "the belief in a universal bond of sharing that connects all humanity". According to some metrics, Ubuntu is the most popular Linux distribution.
Ubuntu. Login to text mode. It is not need to remove GUI from the system.
You can leave it and just make your default boot as a text mode and if once you need a GUI you can restore it so easy.
open /etc/default/grub as and add text to the
sudo nano /etc/default/grub
And in the file, change this line:
Then update your Grub
Your system will then always boot to text mode.
If you once want to use GUI you can easly make light works
sudo service lightdm start