That bottom panel is from the "Window List" plugin.
The gnome 3 classic package depends on that plugin package on CentOS 7 as far as I checked.
And Gnome 3 classic uses it as a required plugin and ignores user settings even if it is disabled.
A dirty fix is to just remove the directory for the plugin:
# rm -r /email@example.com
If you want it back later, you may re-install that plugin's package.
# yum reinstall gnome-shell-extension-window-list