Clear specific http response header before sending

[tinker-ben]

Good day :)

would like to ask if there is a method to Clear specific http response header before sending a response back to client using ESP8266WebServer's server.send();

Reason i'm asking is because when I use:
server.sendHeader(F("Connection"),F("close"));

it is appending to existing keep-alive value of the header:
connection →close, keep-alive content-length →25 content-type →application/json keep-alive →timeout=7000, timeout=2000