Client information (name, address, notes, jobs, invoices) for the life of the company or a judge tells me to remove it from my system with a court order.
Client data (pictures/documents) stays on my server for a week if I do a transfer, afterwards I remove it unless requested by the client.
I've kept data for months for one customer till they were sure it worked out (next quarter taxes). I had one that requested it be deleted on the spot (I make it a habit to not look at customer data but he did have a folder labeled "wifey being hot" that I saw when running the du command (linux command line: disk usage command) to estimate backup time.