Tool to remove image parts in PDF
Maybe think from the opposite side...


Open your PDF  
Select an area you want to keep.  
 Cmd ⌘   C  to copy, then  Cmd ⌘   N  which will open a new document with the clipboard contents.  
Repeat for each section you want to keep.  
Save each of your new sections as separate files. Use the default name, which will number in save order, these will be ephemeral.  
Close everything.  
Select all your newly-saved files in Finder &amp; Open  
They will all open in one window, in file order.  
You can then Print the whole lot as a single document - to PDF.


Requires Preview prefs > General > Open groups of files in the same window