Unused WordPress themes can pose security risks and take up unnecessary space. It is considered best practice to remove old or inactive themes from your website.
Step-by-Step Instructions
Log in to your WordPress Dashboard.
From the left-hand menu, navigate to Appearance > Themes.
Hover over the theme you want to remove and click Theme Details.
In the Theme Details window, click Delete in the bottom-right corner, then confirm by clicking OK.
Notes
Only inactive themes can be deleted. You cannot remove the currently active theme.
Removing unused themes improves website security and reduces clutter in your WordPress installation.
You can always reinstall a theme later if needed.