I think "hoarding" is an OCD or anxiety issue.

I hoard little things but I have to have absolute order or I can't cope. I have receipts dating back to 1996, give or take a year, and I simply can't bring myself to part with them.

Sorry I don't really have any advice. Maybe you could just take some baby steps - maybe pick out one pair of old shoes to throw out or donate to charity and see how it feels.