To remove the GDM (GNOME Display Manager) graphical login screen on CentOS or Red Hat Enterprise Linux, you need to uninstall the gdm package using the yum package manager.
First, use the following command to check if GDM is installed:
yum list installed | grep gdm
If the package is installed, you can remove it using the following command:
sudo yum remove gdm
After removing the package, you may need to configure the system to use a different display manager, such as LightDM or XDM. To switch to LightDM, for example, you can install the lightdm package and enable the lightdm service with the following commands:
sudo yum install lightdm
sudo systemctl enable lightdm
Note that removing the display manager can cause issues with the graphical interface of the system. Before removing GDM, make sure you have a plan in place to manage the display and have the necessary knowledge to resolve any issues that may arise.