Is there a way to customize "disabled members by admin" message?

I don't like the default message that says something about "Administrator has disabled registration for new members."

Is there a way to customize it?

I don't think there is but you can just hide the Register button on your nav bar.

EXCELLENT IDEA. One flaw in the plan tho...

How to do it? XD

Code:

a[href="/register"]{
    display: none;
}

Place that in your CSS.