How to stop the timer?

How to stop the timer?

Hello, I try to stop my timer, but nothing happend.
My Javascript-Code show on the follow:

function Ticker() {
var xhttp;
function create() {
//init xmlhttprequest;
}
function send() {
//send-init
}
function xmlparse() {
//parse xml-file;
callbackTimer(timeOut)
}
create();
send();
}

function callbackTimer(timeOut) {
setTimeOut("Ticker", timeOut);
}

How programm a stop-function to abort the reload-function of the php-file.
Thanks.