Where does Kubuntu/KDE keep references to themes?

I hope this message finds you well.
I've attempted to remove a desktop theme via System Settings > Workspace Theme > Desktop Theme. Clicking the 'Remove Theme' button removes the theme from the list initially. However, upon exiting then returning, the theme is listed.
I've searched for the theme using ...

find . -name '*[Ll]ight*[Ww]arp*'

in the following directories and subs ...

  /usr/share/plasma
  ~/.local/share/plasma

I thought a reference to the theme may be an entry in a config file or stuck in cache but am unsure where to look.

Any assistance is greatly appreciated.

Thank you

UPDATE:

I located references to the 'deleted' theme in colors and metadata-desktop located in

~/.local/share/plasma/desktoptheme/metadata/

colors

[General]
Name=Light Warp
shadeSortColumn=true

metadata-desktop

[Desktop Entry]
Comment=semi-transparent plasma theme
Name=Light Warp

It appears these files were not deleted with the rest of the theme. One thing that bothers me is the files are not in the theme directory ...

i.e. .../desktoptheme/LightWarp/

but in metadata/ located in ...

~/.local/share/plasma/desktoptheme/

with other theme folders.

Hesitant to delete for fear of causing further issues.

Kubuntu                 = 18.04
Release                 = Ubuntu 18.04.3 LTS
KDE Plasma version      = 5.12.9
KDE Frameworks Version  = 5.44.0
QT version              = 5.9.5
Kernel version          = 5.4.0-99-generic
OS type                 = 64 bit

I'm in a more recent version (22.04) where settings are structured differently (so that your options "Workspace Theme > Desktop Theme" don't make much sense on my system), but as far as I can remember the basic levels are the same.

In Plasma the "themes" have more levels than in other desktops, so that, beside icons, cursors and windows decorations, what we see as "the theme" includes at least three levels:

At /usr/share/plasma/look-and-feel and ~/.local/share/plasma/look-and-feel there are "Global themes" (giving the overall look, dark or light look and colors):

As said here, there are the themes stored in:

System/Default: `/usr/share/plasma/desktoptheme/`
User Installed: `~/.local/share/plasma/desktoptheme/.`

which are the "Plasma styles", which determine the look of panel and widgets:

I couldn't find the location of those under "Application style" (influencing the texture, buttons). New ones cannot be installed there from the settings interface like for the rest, but there is where something like Kvantum is listed (which can be installed as a separate application).

But 'Aplication style>Gnome/gtk applications' are in ~/.themes and /usr/share/themes (these are themes for gtk applications).

Cursors and icons are in /usr/share/icons and ~/.local/share/icons.

Window decorations are in /usr/share/kwin/decorations and ~/.local/share/aurorae/themes.

You shouldn't touch the files and folders at system level.

On configuration files see this.