To delete a page from the document, select it, right-click it in the page toolbar (Context menu) and use the command Delete Page.
To move a page up in the document, select it, right-click it in the page toolbar (Context menu) and use the command Move Page Up.
To move a page down in the document, select it, right-click it in the page toolbar (Context menu) and use the command Move Page Down.
Tip: when you load prescanned images into memory, Readiris sorts them automatically - image 001.tif precedes 002.tif precedes 003.tif etc.