For all practical purposes, cancelled trains and deleted trains are the same thing. Cancelled trains don't appear in search and cannot be looked up through the drop-down lists. So these trains don't show up when people are searching for future travel options.
If someone has bookmarked an old link to this train page, then the train will still show up but with the big red Cancelled mark. The train will still be there for history showing at what date the train was cancelled and went out of service.
Thanks.