How can I disable all themes on my Note 9 after Pie update?

[Android Central Question]

Before the update, I was using a black background (just a photo I took) for my wallpaper and lock screen. I believe I was using "night mode" to provide a dark background for my text messages. I've lost both those with the Pie update. I have (foolishly) tried a dark theme, but that doesn't provide a dark background for text messages. And I find that I'm unable to choose night mode because I have a theme enabled. How can I disable the theme?

 

[bbgpsuser]

Open the Galazy Themes app.
After it loads you may have to pull down from mid screen to see the "My themes" at the top.
Select and apply the default theme.

 

[strikeIII]

You can revert back to the default theme. It should be the first theme listed. Also, there are dark themes that will give you a dark background in the text messaging app. I use MINU Black or Black_Edition_V2 theme.