To clarify: I assume that you have a document library with pages in it, and you intend to reimplement "Delete document" ribbon button functionality:
One of the approaches could be to get selected item using SP.ListOperation.Selection.getSelectedItems(), and then use SharePoint Client Object Model to delete it. This is an intended approach.
But also it's possible to achieve the objective using original SharePoint code for 'Delete document' ribbon button. I've done some investigations and found a working solution. But be aware: although it was an interesting exploration, the functionality is undocumented.
So you could notice SP.Ribbon.PageManager.executeRootCommand method call here, and maybe you can try to use it (it is documented and supported), but I was disappointed with the number of parameters of this method and decided to dive even deeper. Because I know undoubtedly, that deletion of a selected item is a very simple operation and all necessary information for the deletion could be retrieved from some page context or global variables or smth like this.
So I came down to the last handleCommand method and then I saw this picture:
Woohoo, here it is,
DeleteSelectedItems, with a context variable passed into it. After a bit of further investigations, I've found out, that this context could be retrieved with the function SP.Ribbon.NativeUtility.getCtxForView, which gets as a parameter the current list view GUID.
So, finally solution is compressed to following js call:
and it works! :)
And after I pressed OK, it actually deleted the selected item.
So, I hope you enjoyed the adventure :)