“Erased writing” (or, an ‘erasure’) refers to a written entry/ies which has been removed in an attempt to get rid of the original information, either to simply delete it or replace it with something else.
An erasure may be achieved manually/mechanically using an eraser, some type of scraping tool, or using an adhesive lifting process (for select types of material). Alternatively, erasures may be achieved chemically through the application of a ‘bleaching’ solution, or some type of lifting agent.
Often the idea behind an erasure is to remove the information, ideally, leaving no significant indication any information was ever present, or that an erasure has occurred. This can be contrasted to an obliteration where the information is covered or masked, often in a relatively obvious manner.
With most erasures there will be physical or chemical signs that one has been done, albeit sometimes very subtle and difficult to see. At the same time, detecting this type of event is one thing. Recovering or deciphering the original information is another, often much more challenging, prospect.