Footwell wet

Hello, I wanted to remove the FRM module and check it. Because it kept getting fake error messages. I noticed that the footwell was completely wet. Now I'm trying to dry it out by putting newspaper between them and using the sunny weather to dry it. However, I still don't know how the water gets in there. There's a tip on the internet.

https://www.youtube.com/watch?v=bJMpjcd25GM

But I don't know how to fix it. I just vacuumed it out. But I don't know if it's clean now. Can I just pull out this "drain pipe"?

Thank you for any tips

Best regards

Stefan