You can of course de-select the X sets during system installation but this not recommended if you intend to use any ports.
Most ports have a dependency on X. This even includes some applications that don't have an X interface. The OpenBSD FAQ entry probably explains why you may still want X the best:
Why do I have to install X for my non-graphical application?
Even if you have no intention of running X, some third party packages require the libraries or other utilities in X to be installed on your system. These applications can sometimes be satisfied simply by installing just xbase57.tgz, the rest of X is not always needed. Many people resist installing X on their system without valid reason:
- By itself, installing X does not cause any program to execute on the system.
- By itself, installing X on a system does not change the risk of external security issues.
- If someone is already ON your system, they can most likely install whatever they wish, so the presence or absence of the X does not appreciably change the situation.
- The only parts of X that are running are the parts required by your application.
- The space required for X is relatively modest on modern hardware.
People sometimes waste a lot of time and effort trying to pick through xbase57.tgz and pull out just the files they need to install their application. This is not only pointless, but an effort that would have to be repeated for each upgrade cycle, which probably means you will not upgrade your system properly, creating REAL security problems. IF you need X, just install it. It won't hurt you any more than the application you are needing it for will.