Deleting a Theme
You can delete the JSON definition of a theme for the Composer UI. You must know the theme ID before you can delete it.
To delete a theme:
Obtain the theme ID. You can do this by listing the themes in your environment. See Listing Themes.
/api/customization/themes/<id>API endpoint in a DELETE request to delete the theme. The following request deletes the theme named mytheme.
curl -X DELETE "http://<ip-address>:<port>/composer/api/customization/themes/mytheme" -H "accept: application/vnd.composer.v2+json"
<ip-address>is the IP address or host name of your Composer instance and
<port>is its port.
The theme is deleted.