如何使用我的php变量UserNameID删除数据库中的用户行

I want the user to be able to remove their account from the database, this will be done by the click of a button in my php forum, see code below.

  <div  class="btn-group">
    <button style="width:200px" type="button" class="btn btn-primary">Change details</button>
    <button style="width:200px" type="button" class="btn btn-primary">Add details</button>
    <button onclick="myFunction()" style="width:200px" type="button" class="btn btn-primary">Delete details</button>
    </div>

I already have the database connection setup

<?php
$connection = mysql_connect('localhost', 'root', 'Oliver'); 
mysql_select_db('users');    
$query = "SELECT * FROM username WHERE username='$login_session'"; 
$result = mysql_query($query);       
while($row = mysql_fetch_array($result)){      
$name = $row['name'];
$username = $row['username'];
$sex = $row['sex'];
$phone = $row['phone'];
$email = $row['email'];
$dob = $row['dob'];
$image = $row['imagelink'];
$hobby = $row['hobby'];
$bio = $row['Bio'];
$Level = $row['Level'];
$UserNameID = $row['UserNameID'];
}    
mysql_close(); 
?>

The database row will be identified by the php variable UserNameID which is from the database

$UserNameID = $row['UserNameID'];

If you need any more info please just drop me a response, i'm quite new to coding so cooperation will be needed :D Thanks ever so much

Update Instead of disliking please tell me what i'm doing wrong, that would be hugely appreciated

Update

This is the session code

<?php
// Establishing Connection with Server by passing server_name, user_id and password as a parameter
$connection = mysql_connect("localhost", "root", "Oliver");
// Selecting Database
$db = mysql_select_db("users", $connection);
session_start();// Starting Session
// Storing Session
$user_check=$_SESSION['login_user'];
// SQL Query To Fetch Complete Information Of User
$ses_sql=mysql_query("select username from username where username='$user_check'", $connection);
$row = mysql_fetch_assoc($ses_sql);
$login_session =$row['username'];
if(!isset($login_session)){
mysql_close($connection); // Closing Connection
header('Location: home.php'); // Redirecting To Home Page
}
?>

This just logs the user in if details are match in the database and starts a session to unlock other pages

I think this will move you bit closer to your goal.

<div class="btn-group">
    <button style="width:200px" type="button" class="btn btn-primary">Change details</button>
    <button style="width:200px" type="button" class="btn btn-primary">Add details</button
    <form action="" method="post">
        <button type="submit" style="width:200px" class="btn btn-primary">Delete details</button>
        <input type="hidden" name="UserName id="UserName" value="<?php echo $login_session;?>" />
    </form>
</div>

<?php
$connection = mysql_connect('localhost', 'root', 'Oliver'); 
mysql_select_db('users');    
$query = "SELECT * FROM username WHERE username='$login_session'";
$result = mysql_query($query); 
//By the way you don't need loop here      
    while($row = mysql_fetch_array($result)){      
        $name = $row['name'];
        $username = $row['username'];
        $sex = $row['sex'];
        $phone = $row['phone'];
        $email = $row['email'];
        $dob = $row['dob'];
        $image = $row['imagelink'];
        $hobby = $row['hobby'];
        $bio = $row['Bio'];
        $Level = $row['Level'];
        $UserNameID = $row['UserNameID'];
    }
    //Here you delete record from database
        if(isset($_POST['UserName'])){
        $user = mysql_real_escape_string($_POST['UserName']);
        //Strongly suggest that use UserId to delete record not username
        $sql = "DELETE FROM username WHERE username='$user' LIMIT 1";
    }       
mysql_close(); 
?>

Edited According to OP request

<?php
$connection = mysql_connect('localhost', 'root', 'Oliver'); 
mysql_select_db('users');
if(isset($_POST['UserName'])){ 
$user = mysql_real_escape_string($_POST['UserName']);
$query = "SELECT * FROM username WHERE username='$user'";
$result = mysql_query($query);
$total = mysql_num_rows($result);   
$row = mysql_fetch_array($result);
// You dont need to fetch all records just `$UserNameID` enough
$name = $row['name'];
$username = $row['username'];
$sex = $row['sex'];
$phone = $row['phone'];
$email = $row['email'];
$dob = $row['dob'];
$image = $row['imagelink'];
$hobby = $row['hobby'];
$bio = $row['Bio'];
$Level = $row['Level'];
$UserNameID = $row['UserNameID'];

//Here you delete record from database
    if($total>0){
        $sql = "DELETE FROM username WHERE UserNameID='$UserNameID' LIMIT 1";
    }
}
mysql_close(); 
?>