Disable Proxy Preserve Host on Haproxy

i need to disable the origin Host header routed from haproxy to the backends ? can someone pass the syntax that needs to be used in order to disable the Preserve Host.

You can overwrite the header with http-request set-header in the frontend:

http-request set-header www.example.org

i do not need to set a header looking for a replacement syntax used in Apache Proxy Preserve Host Off

I understand, that is what this is.

ProxyPreserveHost Off means that Apache replaces the Host header with whatever hostname is specified in the ProxyPass line.

In Haproxy, there is no proxypass line. You specify the Hostname with:

http-request set-header www.example.org