File permission of composer folder changed to 000 by itself. And now I am unable to change it or delete this folder. Folder is located at htdocs/core/vendor/composer
If a file permission has been changed to 000, there is nothing that anyone can do to revert it, as everyone is not locked out. You will have to create a new hosting account if you want that folder gone, or its contents edited.
No one can help you. You need to create another hosting account and transfer your website