To remove footer credit
1.Click Appearance > Customize
2.Go to Footer Option
3.Go to Copyright option and edit
4.Go to Power by option and edit
Footer credit can be omitted from WordPress admin but if your theme does not have the option to remove or modify footer credits from WordPress admin, then your only option is to edit the footer.php code.You can find this file in your /wp-content/themes/yourtheme/footer.php
You can either remove this text entirely or customize it to suit your needs.