How can I reset this? Disclaimer: When I'm referring to "it" I mean the Dark interface!!

I saw that Youtuber that had his Blender looking different. He then told me how he did that (It was something that comes with Blender).

I then activated it, but now i want to disable it. I already tried to reinstall Blender and even delete the Blender foundation folder but nothing worked...
Can you please help me?
You can change the theme from dark to light in the preferences. Open Edit > Preferences then go to Themes and select Light from the dropdown. The dark theme is the default in Blender 2.8.