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Old macro workbook from Microsoft samples gallery left items on the ADD-INS ribbon tab, highlighted by yellow:

These cannot be deleted or at least I don't know where to find them – see Customize Ribbon window open on the screenshot – they are not there.
Items are bound to still functional macros, but I can't find their code. There is nothing in top-left pane (which shows list of VBA modules) in VBA IDE.
I have checked all Addin types in Excel Options > Add-ins, they are not there.
I have checked Add-ins and COM Add-ins items on ribbon's DEVELOPER tab, these do not contain it.
I have checked Addin Manager in VBA IDE, it is empty.
I checked for hidden workbooks in View tab (thanks @AlexFrolov) and Unhide button is disabled.
The only list I did not check was list of Automation Servers due to its length (it can be opened using Add-ins window).
ADD-INS ribbon tab is missing only in Excel Safe mode but unwanted icons are always present in standard mode.
How can I delete this toolbar labeled "Custom toolbar" from ADD-INS ribbon tab?
Sounds like an add-in customized the ribbon UI, which is done via xml. see info in this SO thread. Given I've never used this feature of excel, I can't think of how to help. Look up on how to reset the xml that powers the ribbon UI.
– Raystafarian – 2014-05-13T12:49:08.043Here is the MS KB on ribbon xml, I'd look there to find the default and reactivate it. – Raystafarian – 2014-05-13T12:51:05.330
1Please check if you have any hidden workbooks (like Personal.xlsb) opened:
Viewtab ->Windowgroup ->Unhide. – Alex Frolov – 2014-05-13T14:29:42.250@AlexFrolov I didn't even consider the fact that it may be calling from the personal macro workbook. +1 – Raystafarian – 2014-05-13T19:34:51.267
1My best guess is a ribbonui element that has stored itself in the default template. Open a different template and see if the ribbon is still there. If not, find the default template file and delete the XML by unzipping the file and searching for it. – wbeard52 – 2014-05-14T06:45:07.253
@AlexFrolov – the control is disabled. I have edited the question to make it more complete. Thanks. – miroxlav – 2014-05-14T09:06:23.140
@Raystafarian – let me try this a bit later and then come back with feedback. – miroxlav – 2014-05-14T13:16:36.220