Authored Comments

This part you are describing usually consists of two parts. username@hostname.
If you want to shorten that part you have the options of shortening either your username or the hostname of your system. In your example your hostname is really long so I would suggest that you find an online resource that describes how to change your username on your distro.
If you are using ubuntu (because of your linked tutorials from above) you can use the hostnamectl tool in your terminal. Simply type sudo hostnamectl set-hostname to set a new hostname for your machine.
A more detailed description of the hostnamectl tool and more ways to change your hostname can be found in those articles:
I hope you found the answer you looked for :)