Your server signature is on... according to an SEO Test

Several SEO tests have thrown this up and it would seem super easy to fix and just make it go away (pass instead of fail)

Your server signature is on. Turning off your server signature is generally a good idea
from a security standpoint. Read more on how to turn off server signature and improve
your website's security.
 Server: Microsoft-IIS/8.5
HOW TO FIX SERVER SIGNATURE TEST
By default, the Apache webserver sends HTTP headers with some information about your
server version, operating system, modules installed, etc. These informations can be used
by hackers in order to exploit vulnerabilities (specially if you are running an older
version). These information can be hidden or changed with very basic configurations.
Open Apache?s configuration file (httpd.conf or apache.conf) and search for
ServerSignature. If you find it, edit it to:
ServerSignature Off
ServerTokens Prod
If you don't find it, just add these two lines at the end of the file.
Note that, after you modify the configuration file, you must restart the Apache server.