There's going to be a time, where you forget the password, and other series of problems like:
I know I have. So here's what you can do.
1. Copy to functions.php, remember to change "Hello World". Change user ID accordingly.
$user_id = 1;
$password = 'HelloWorld';
wp_set_password( $password, $user_id );
Paste this under <?php in functions.php.
2. Go to default URL.
3. Go back to function and delete what you've pasted.
4. Go to wp-admin, use the new password.