The default Twenty Seventeen site footer has information text stating "Proudly powered by WordPress' that links to wordpress.org. The text and link can be changed.

The default 'Proudly Powered by WordPress' footer text and link.

The changed footer text and link.

Where and how to change or remove the footer text and link:

Make sure you are using a child theme for Twenty Seventeen on the server. Click here to learn how to create a child theme.
On your server's WordPress installation, go to the WordPress Root > wp-content > themes > twentyseventeen > template-parts > footer, and download the file 'site-info.php'.

Open the file in your preferred text editor (I use EditPad Pro) and change the PHP code as follows.

Change this PHP code:

<?php
/**
 * Displays footer site info
 *
 * @package WordPress
 * @subpackage Twenty_Seventeen
 * @since 1.0
 * @version 1.0
 */

?>
<div class="site-info">
	<a href="<?php echo esc_url( __( 'https://wordpress.org/', 'twentyseventeen' ) ); ?>"><?php printf( __( 'Proudly powered by %s', 'twentyseventeen' ), 'WordPress' ); ?></a>
</div><!-- .site-info -->

To the PHP code below:

<?php
/**
 * Displays footer site info
 *
 * @package WordPress
 * @subpackage Twenty_Seventeen
 * @since 1.0
 * @version 1.0
 */

?>
<div class="site-info">
	<a href="https://karavadra.net">Customized by Bharat Karavadra</a>
</div><!-- .site-info -->

The new link in the code above is https://karavadra.net and the new text is Customised by Bharat Karavadra
To remove the text and link entirely, delete the whole line beginning with '<a href='
In the folder of your child theme at WordPress Root > wp-content > themes > twentyseventeen-child, create a folder called 'template-parts'. In that created a folder called 'footer'.
Now upload the edited 'site-info.php' file to the new 'template-parts folder', as above, in the child theme.

That's it.