My oldest items are a couple of T-shirts from high school. I just keep them for sentimental reasons.
I usually do a major purge when I move. For items in good shape: I have sold on E-bay and consigned items, or given to friends who wanted them. The rest I donated to Goodwill. Anything that is worn out, stained or has a hole I threw out.
I am getting ready to move so I will be facing this again soon.