How to remove an appimage's user mofied settings after or before deleting the appimage file?

I launched an appimage using appimagelauncher. Then, I modified some settings of that app.

I know that appimages are not installed, so it can't be uninstalled. So, I deleted the appimage file.

But, when I downlaoded the appimage again, I observed that the user's previously modified settings were still there.

Now, how can I completely remove those user modified settings and launch that software as if it were newly installed?

The AppImage format doesn't define an explicit place where the applications configuration should be installed. Which means that the application can write such file wherever they please (as a regular installed application does).

Applications usually write their configurations to "$HOME/.config", you can look there for a file or folder with the application name. You can also ask the application author or check the documentation.