Unable to delete SharePoint 2013 Masterpage from Masterpage and Page Layout Gallery.

Hi,

            I have deployed a New MasterPage using wsp in my SharePoint 2013 Environment. After some  (Look and Feel/Branding) issue I have removed the wsp and reset the my MasterPage as seattle with option "Reset all subsites to inherit this site master page setting". Then Deactivated the MasterPage's feature from Site settings --> Site Collection Administrator --> Site Collection Feature. Now I tried To delete the Master Page from Site settings --> Gallery -->  Masterpage and Page Layout. When I tried to Delete the MasterPage.master file. I got the below error,

Can not delete a master page "This item cannot be deleted because it is still referenced by other pages".

So I again Reset the MasterPage as seattle and checked "Reset all subsites to inherit this site master page setting".  Again I got the same error. I'm sure this master is not referencing anywhere.

I checked the path http://sitename:port/_catalogs/design/AllItems.aspx. It has only Seattle and oslo master and that corresponding files. It not had any file related to my MasterPage.master.

I done the below steps to delete

1. I created a new folder called DeleteMaster and moved MasterPage.master file inDeleteMaster and tried to delete DeleteMaster, but no use,

2. Tried http://support.microsoft.com/?kbid=926812, this Microsoft link also not helps me.

 Please help to me to delete .master file from gallery

Loganathan S