To redeem the collateral, the debt must be repaid with USDJ along with a stability fee paid with JUST platform token, JST. After the repayment is done, the CDP holder can send a transaction to JUST to retrieve all collateral assets.
If the the price of the collateral drops so drastically as to be unable to satisfy the debt, the CDP liquidation will be triggered and the collateral will be auctioned by the system to repay the debt.
The remaining collateral net of repayment and penalty, if any, will be kept in the CDP and available for collection.