Добавляем в /etc/httpd/conf/httpd.conf или /etc/httpd/conf.d/tokens.conf

ServerSignature [параметр]
ServerTokens [параметр]

expose_php - Выдает факт присутствия PHP на сервере, включая передачу версии PHP в HTTP-заголовке.

Server: Apache/2.4.6 (CentOS) ... PHP/5.4.16

Для скрытия версии PHP в файле /etc/php.ini устанавливаем

expose_php = Off

Помимо этого убрать заголовки Powered-By для nginx/fpm можно так

fastcgi_hide_header    X-Powered-By;
fastcgi_hide_header    X-CF-Powered-By;

wget

$ wget -S --spider http://foobar.com

Connecting to foobar.com (foobar.com)|192.168.100.25|:80... connected.
HTTP request sent, awaiting response... 
HTTP/1.1 200 OK
Date: Tue, 24 Dec 2019 14:37:11 GMT
Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips mod_fcgid/2.3.9 PHP/5.4.16
Last-Modified: Tue, 24 Dec 2019 14:16:40 GMT
ETag: "1321-59a73caed0200"
Accept-Ranges: bytes
Content-Length: 4897
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8
Length: 4897 (4.8K) [text/html]

curl

$ curl -I http://foobar.com

HTTP/1.1 200 OK
Date: Tue, 24 Dec 2019 14:37:11 GMT
Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips mod_fcgid/2.3.9 PHP/5.4.16
Last-Modified: Tue, 24 Dec 2019 14:16:40 GMT
ETag: "1321-59a73caed0200"
Accept-Ranges: bytes
Content-Length: 4897
Content-Type: text/html; charset=UTF-8

lynx

$ lynx -head -dump http://foobar.com

HTTP/1.1 200 OK
Date: Tue, 24 Dec 2019 14:37:11 GMT
Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips mod_fcgid/2.3.9 PHP/5.4.16
Last-Modified: Tue, 24 Dec 2019 14:16:40 GMT
ETag: "1321-59a73caed0200"
Accept-Ranges: bytes
Content-Length: 4897
Connection: close
Content-Type: text/html; charset=UTF-8