All praise is due to Allah and may Allah shower peace and blessings upon His Messenger, as for what follows.
The answer to the questioner's inquiry, in which he mentions that he embraced Islam and has some wealth derived from usurious (interest-laiden) financial transactions during his time as a Non-Muslim, so what does he do with it? We respond saying:
Whatever usurious monies or transactions were a part of his wealth during his period of Kufr (disbelief), he is not at fault for them.
Also, any transactions set into motion during his period of Kufr and then continued after accepting Islam, and these contracts continue between him and others (like usurious loans and sales), then it is not allowed for him to benefit from them and he has no claim to those benefits and must only take what Islam has allowed for him to take, which is the initial capital.
This is due to Allah's statement, "... and if you make Taubah (repentance). you shall have your capital sums. Deal not unjustly (by asking more than your capital sums), and you shall not be dealt with unjustly (by receiving less than your capital sums)..." [al-Baqarah 2:279]
Also, the Hadith during the Prophet's - sallAllaahu `alayhi wa sallam - fairwell Hajj (pilgrimage), "Verily, all usurious dues accruing from Jahiliyyah (pre-Islamic era) stand wiped out. And the first amount of interest that I remit is that which Abbas bin Abdul Mutallib had to receive. Verily, it is being remitted entirely. You shall have your capital sums. Deal not unjustly, and you shall not be dealt with unjustly."
And all praise is due to Allah, Lord of the world
After answering the question, the Shaikh added:
The Prophet -sallAllaahu `alayhi wa sallam - never ordered those who embrace Islam -from the Sahabah- to get rid of the usurious monies from their (existing) wealth.