I can not access htdocs

I created a new account, and the htdocs directory was automatically created. I uploaded files to this directory. However, I then added a new domain, and it created another htdocs directory. And now I’m having the problem of when I access my site www.mydomain.com, it does not access the htdocs directory that is with the files I’ve uploaded.
So far I have tried to delete the directory created after adding the domain via FTP, and the error 550 can not remove directory: Permission denied appears. I tried to change the permission to
CHMOD 777 but I could not do it either.
What should I do to access htdocs normally?

Images to better understand https://drive.google.com/file/d/1w4EbFfNLYYHZk9SbOAv2B88c6dur5xpk/view?usp=sharing


Maybe this topic will help:

I see you’ve already created a new account for this particular domain. Is this question still relevant?