Where do i recycle my old leather belt?

If it is still usable, donate it to a local charity.

If it is in need of repairs of some sort, check to see if there is a shop in your area which accepts items for donation and then resale for 'creative re-use.'

I live in California, in the S.F. Bay Area; there are several stores like that around here.

Take it to your local charity shop. If they decide it is not in a good enough condition to sell in the store they can still send it away for use in overseas market stores or recycle it into industrial fibre for use in dish cloths and mops.

I would recommend giving it to a charity such as the Salvation Army rather than taking it to a supermarket textile recycling point as these are sometimes owned by private companies.