How to delete firebase child data in Javascript?

The script is like this to show the data from firebase database:

const onChildAdd = (snap) => { $('#contacts').append(contactHtmlFromObject(snap.key, snap.val()));}

//prepare contact object's HTML
const contactHtmlFromObject = (key, contact) => `
<div class="card contact" style="width: 100%;" id="${key}">
<div class="card-body">
    <button class="arrival btn btn-danger btn-xs" onclick="delete_user()">X</button>
  <h5 class="card-title">User: ${contact.a2}</h5>
  <h6 class="card-subtitle mb-2 text-muted">User1: ${contact.a3}</h6>
  <p class="card-text" title="${contact.a1}">
   Expiry:${contact.a1} - Vip:${contact.a4} - Status:${contact.a5}
  </p>
  <input type="text" class="form-control" id="kea" value="${contact.a7}">
</div>
 </div>`;

const spanText = (textStr, textClasses) => { const classNames = textClasses.map(c => `text-${c}`).join(' ');
return `<span class="${classNames}">${textStr}</span>`;}

I also have a function:

function delete_user() { firebase.database().ref().child("contact/" + auth.uid + "/" + $('#kea').val()).remove();
alert('The user is deleted successfully!'); }

I use input text to show my child key -Kvhovcjoggiobhuoy something like this or whatever.

I'm trying to delete child key with function delete_user() when click the button.

Any way to correct it, or any other way to delete it?