Must one dispose of possessions acquired from working at the Social Security Fund – which deals with usury – after repenting and resigning from it, or does repentance supersede what came before it?

If you were unaware that the work contained prohibitions, then left it as soon as you became aware and repented, what you earned is permissible. However, if you knew about the prohibitions and were negligent, then you must dispose of the money earned from forbidden matters by spending it on public interests and good deeds, unless you are in need of it, in which case you may spend from it as much as needed. You are not required to dispose of the house or the things you bought with the money earned from that work.