I believe as @MattIPv4 said, most probably you are referring to the hostname of the server. Please note this is just a cosmetic change and you can always actually change the hostname directly from your droplet.
What I’ll recommend is to create the droplet with a random name for a hostname and I’ll show you how to change it.
In Ubuntu 18.04 we can change the system hostname and related settings using the command hostnamectl.
To change the system static hostname to TestingHostnameChange, you would use the following command:
sudo hostnamectl set-hostname TestingHostnameChange
1. Change the hostname using hostnamectl.
The hostnamectl command does not produce output. On success, 0 is returned, a non-zero failure code otherwise.
2. Edit /etc/hosts.
The file will look something like that
# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
Notice where I’ve added under localhost the new name of the server.
That’s it, you are ready.