Worpdress pulgin to customise CMS side bar options?

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Does anyone know of any WP plugins to customise the side bar options within the CMS? (please note I'm not talking about widgets or customizing side panel of the web pages). I'm talking about the actual CMS side bar settings.

I recently purchased a theme that had a Gallery option but because I installed a contact form plugin it replaced the gallery option within the CMS.

Plugin or advice on how to get this Gallery option back is appreciated.