ubuntu www-data group member delete file permission problem

I created this folder in php with

mkdir($folder, 0770, true)

my user

sudo usermod -a -G www-data my_user

folder permissions

ls -l /var/www/html/test/1/ 

-rwxrwx--- 1 www-data www-data

After that i can’t delete this folder with my_user in ftp or ssh connection in vs code.

“permission denied” error returned.

if i change the folder owner to my_user then i can delete the folder. my_user also member of www-data. with 770 attributes, shouldn’t it be possible to delete the file as a group member without being the owner?