You could add a Boolean Attribute (isVisible) to the Entity of your first DataGrid. Set the default value to True. Then set the Visibility of the Datagrid on this Boolean. ( $currentObject/isVisible = true )
When you click in a row, call a Microflow. In this Microflow use a ChangeObject Activity and set the Boolean isVisible Attribute to false.
The First DataGrid should be hidden now.
Hope this Helps,