You need to be the network administrator, here’s a tutorial that shows how to give a user super admin access: https://premium.wpmudev.org/manuals/wpmu-manual-2/working-with-super-admin-users/
BTW: In order for us to help you as fast and efficiently as possible, I would like to invite you over to our help desk where you can safely share your website link and login details if necessary. Using our help desk it keeps everything super organized to keep the conversation going.
Please register at our help desk or you can browse our theme resources centre which contains many detailed video tutorials and theme documentation. Once logged in, feel free to create a new support ticket here.
We are looking forward to helping you over on our help desk.
