Gnome setup RHEL-8

We have need to do two things, as we have been able to with previous versions.
1. remove the close "X" from all windows.
attempts using dconf-editor, gsettings and tweaks seem to succeed
but are having no effect.
2 remove the 'activities' button, and remaining items on the top bar of
the initial window. We run a standalone application, and access to
the OS and other utilities is strictly controlled from within