REORDER, ROTATE, DELETE, and ADD PAGES
You can delete or rotate single pages or multiple pages at once (hold Control or Command to select more than one) and click on the trash can icon at the bottom of the column to delete the page(s) or click on to rotate the page(s) 90 degrees clockwise (as many times as needed). To rotate all pages at once, click on the File menu button in the upper right corner and hover your cursor over Actions Rotate Pages and choose an option (90 degrees CW or CCW or 180 degrees). To reorder pages, you can simply click on any page and drag it up or down in the order. To add a new, empty page to the end of your PDF, use File menu Actions Append Pages and choose Append Blank Page. Or, you can click on the icon at the bottom of the Page Controls column.
MERGE OR COMBINE FILES
DocHub is also a PDF file merger app which lets you combine or merge or multiple PDFs into one or append a PDF or blank page to the bottom of an open document in DocHub. To do this with an open file, just click on the File menu button in the upper right corner and hover your cursor over Actions Append Pages and click on Merge and Append File, and it'll bring up a window to choose a file from your Computer (select one or drag/drop), Google Drive , Dropbox, OneDrive, or from any 3rd party document URL. Or, you can click on the Page Controls button and use the action buttons at the bottom of the layout of pages for your document. The Append option has a paper icon with a plus sign in the middle. You can combine and merge as many files as you'd like, and you can also rearrange, rotate, and delete any pages after the files have been combined (see the section above this one for more information on how to do those).