The detailed documentation is provided with the tools used to build the solution. Look at Validation Toolkit (server validation), DataAssist, and Universal Email documentation for details on how the page was made from a tools perspective.
Any field is accounted for in several places, so you would have to delete it from all relevent locations.
For any given field there is:
2) Server validation which can be edited by hand on top of the page and the line removed, or you can edit with the Server Behaviors if you have Validation Toolkit installed.
3) Database insert server behavior (documented with DataAssist)... that server behavior would need to be updated to remove the extra fields referenced.