I am new to the WordPress site. I have installed a theme Schema. I have added many users on my site. Now I want to delete and change the username and author. Can you help me
You’ve just shared the link where it is explained in your own post. Just go to your admin / Users and do whatever you want with all those users there.
To change the author of an existing post, go to your admin area > Posts . Click on Quick Edit > Author and from the drop-down menu choose the new author and click on Update .