How can I rid myself of riba (usury) when I withdrew my money from the post office after years of taking profits and bought gold with it?

If you received profits while unaware of their impermissibility, and then learned about it and ceased, there is no blame upon you for what you took, due to Allah’s saying: "So whoever receives an admonition from his Lord and stops, له what has already passed, and his affair is to Allah." However, if you knew of its impermissibility beforehand, then what you took from those usurious profits is not lawful for you.