How to remove the header X-Powered-By for all websites hosted in Plesk for Linux?
# curl -I https://example.com
HTTP/1.1 200 OK
Date: Tue, 01 Jun 2017 00:00:00 GMT
Content-Type: text/html; charset=UTF-8
Go to Extensions > My Extensions > Panel.ini Editor (Open button) > switch to the Editor tab.
Add the following lines at the end of the file:
xPoweredByHeader = off
Go to Tools & Settings > Diagnose & Repair and click repair for Web & FTP Servers to rebuild web-server configuration.