How to enable the button "Save and Close" again after hiding it via sandbox

Summary:

The "Save and Close" button could not be enabled after hiding it via sandbox.

Content (required):

The "Save and Close" button is being hidden per client request, and we have done it via sandbox, while after that we would like to reverse the change and enabled the button again, while it turns out the configuration in that region could not be reset and the button could not be enabled again.

I have tried updating the option via sandbox structure, region "simplepanel" as well, while the update in the simple panel could not be reflected, and thus "Save and Close" button still not being enabled.