Sometimes when you modify a theme but want keep update of the original theme, you could rename it to keep both of them.
Well, cut the crap, let’s go to our main topic: How to rename a theme name in WordPress.
1. Rename the theme folder. Inspect FTP side, go to WordPress directory under wp-content > themes, rename the theme folder.
2. Open the theme file Style.css as editable, find the keyword “Theme name:” on the top, change the name as you want.