A few years ago I invested a small amount in Cryptocurrency. I have recently read Agha Sistani says cryptocurrency trading is not permissible, and I was not aware of this at the time that I made my investment. It has gone up in value, I would like to understand what my next steps are? Am I able to withdraw my investment and the profit for my personal use and close my account? Or should I keep the original investment amount and donate any profits to Sadaqah?

You can keep it, and no need to donate the profits, except if you wish to do so.