Delete the WordPress themes you don't use

TL;DR

On an Astra site, the Themes screen only needs two themes: Astra and your child theme. Most major WordPress updates add a new default theme (Twenty Twenty-Five and so on). When one turns up, delete it, so there's less to update and fewer themes that could carry a security flaw.

Where the extra themes come from

WordPress puts out a new default theme most years, named after the year it comes out. When your site gets a major WordPress update, the new default theme is often installed along with it, even though nobody chose it. A few years on, the Themes screen can hold five or six themes, and only one of them is being used.

Why it’s worth tidying

Every installed theme needs updating, active or not, so extra themes mean more update notices and more to check. An inactive theme with a security flaw can still be a problem, because its files are still on the server. A short list also means anyone who opens the Themes screen can see straight away what runs the site.

What to keep, and what to delete

On an Astra site, keep two themes: Astra, the parent, which must stay installed, and your child theme, the active one where your changes live. If you don’t have a child theme yet, read Use a child theme so Astra updates keep your changes.

To delete anything else, go to Appearance, Themes, click the theme, then click Delete in the bottom right corner. Check again after each major WordPress update, because a new default theme might have been added.

Questions

Is it safe to delete the Twenty-something themes?

Yes, as long as they're not active. Your site uses the theme that's marked Active, and deleting an inactive theme doesn't change any page. Only delete themes you can see aren't in use.

Can I delete Astra if the child theme is active?

No, keep it. The child theme needs Astra to work, and WordPress won't let you delete a parent theme while its child theme is active.

Site Health says I should keep a default theme. Should I?

Site Health suggests keeping one default theme as a backup in case your main theme breaks. If someone looks after your site and keeps backups, you can skip it. If you look after the site yourself, keeping the newest default theme is fine. Delete the older ones.

Can an editor do this?

No. Only administrators can delete themes. If you're an editor and you see extra themes, let whoever looks after your website know.