When you create a field group there is a setting “Hide on screen”. In this box if you want to hide the content editor you tick that box.
However, the hide on screen settings will only be effective for the first field group on the screen. The first field group is according to menu order, if all of your field groups have a menu order of 0 then it will be the field group you created last (reverse date order). You can see the order that the groups are loaded by going to the list of field groups. They will be loaded on edit screen in the same order that they are listed there (/wp-admin/edit.php?post_type=acf-field-group)
