This is a quick and easy method to disable the splash screen on Ubuntu versions 18.04+ (possibly others). Depending on your preference, you may prefer to see the text based status messages that are ubiquitous with the Linux boot process.
sudo sed -i -e 's/GRUB_CMDLINE_LINUX_DEFAULT=""/GRUB_CMDLINE_LINUX_DEFAULT=""/' /etc/default/grub
sudo apt remove plymouth-theme-ubuntu-text
Reboot and you will no longer be greeted with the Ubuntu splash screen.
Alternatively edit the /etc/default/grub file and make changes there.