The alternative to using a child theme is to make two adjustments to the current theme although technically only one is actually required.
- Update the theme name in the theme’s style.css file in the commented section at the top, sometimes referred to as the theme’s headers.
- Rename the theme’s main folder, ie.
wp-content/themes/THIS-THEME-NAME
#1 is required, the second is optional, but advised so you don’t clash with any new copies of the original theme that may get uploaded(which would overwrite your changed version).
NOTE: If you plan to make these changes to a theme, switch to another theme momentarily on the installation whilst doing so, otherwise your database will get left holding incorrect data on the currently active theme(technically it should cause a theme reset anyway, but it would be the better practice to switch theme before making the changes).
Personally i think the child theme approach is safer, but seeing as you’ve already modded the theme that’s potentially hours of work to re-add all the custom code into new files(in the form of a child theme), so hopefully the above is helpful.. 🙂