添加后如何删除事件侦听器

在添加事件监听器后,我试图从按钮中删除事件监听器,最像是重写之前的代码,但它不起作用,我试图控制台日志,但它给出了 undefined ,不知道为什么。我做错了什么/错过了什么?

应用程序。js

document.querySelector("button").addEventListener("click", function(){
    document.querySelector(".dialog").style.display = "block"
    setTimeout(()=>{
        document.querySelector(".dialog").style.display = "none"
    }, 2500)
})
document.querySelector("button").removeEventListener("click", sayHi);
function sayHi(){
    console.log('hello')
}

指数html

    <div class="container">
        Lorem, ipsum dolor sit amet consectetur adipisicing elit. Voluptate in illo omnis vitae molestias natus eaque necessitatibus molestiae nesciunt illum!
        <button>find out more</button>
    </div>

    <div class="dialog" style="display: none;">
        <div class="context">
            <h1>Hi!</h1>
        </div>
    </div>

应用程序。css

.container{
    width:500px;
    height: auto;
    margin:0 auto;
}
button{
    margin:20px auto;
    display: flex;
    justify-content: center;
    cursor: pointer;
}
.dialog{
    width: 100%;
    height: 100%;
    background: black;
    opacity: 0.8;
    position: absolute;
    top:0;
    left:0;
    display: flex;
    justify-content: center;
}
.context{
    width: 400px;
    height: 400px;
    background: white;
    margin: auto;
    display: flex;
    justify-content: center;
    align-items: center;
}