Zoho Desk deletes merged tickets. Which is not ideal. 

The issue is if you have a link bookmarked, or even in your inbox from a ticket that was merged, when you visit you receive an error because merging tickets actually deletes the ticket that was merged. Makes no sense.

So if you go to a merged ticket, this is what you see:

Ideally, when a ticket is merged, the "deleted"/merged ticket's URL redirects to the ticket that it was merged into.