Removes an HTTP header previously set using header.
The header name to be removed. When null, all previously set headers are removed.
This parameter is case-insensitive.
No value is returned.
This function will remove all headers set by PHP, including cookies, session and the X-Powered-By headers.
Headers will only be accessible and output when a SAPI that supports them is in use.
|8.0.0||name is nullable now.|