You can follow below steps on how to safely rename the WordPress theme without using any plugin.
Step 1: In this example, we want to rename the current active theme in WordPress. Before we do that, we need to deactivate the current theme and activate the secondary theme (twenty twenty – default WordPress theme).
Step 2: Once deactivated, go to below directory and rename the theme name folder. You can use WinSCP to perform this activity.
/wp-content/themes
Step 3: Open the style.css file and rename the theme name. You can leave others to the default values. Click on save.
Theme Name: RENAME YOUR THEME HERE
Text Domain: yourthemename
Version: xx
Requires at least: xx
Requires PHP: xx
Description: YOUR-DESCRIPTION on the WORDPRESS THEME
Tags: OPTIONAL
Author URI: https://YOUR-WEBSITE.com
Theme URI: https://YOUR-WEBSITE.com
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Step 4: Now, go back to the themes selection page and re-activate your renamed theme.
