custom-enabled-themes is a variable defined in `custom.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

List of enabled Custom Themes, highest precedence first.
This list does not include the `user' theme, which is set by
Customize and always takes precedence over other Custom Themes.

This variable cannot be defined inside a Custom theme; there, it
is simply ignored.

Setting this variable through Customize calls `enable-theme' or
`load-theme' for each theme in the list.

You can customize this variable.