1. The mortgage loan is between you and the bank. The bank lends you money all at once and you pay it back over time.
The bank has fulfilled its obligations. Therefore, termination of the mortgage is not allowed.
2. If you have a dispute with the developer, you can initiate a lawsuit against the developer through the court to terminate the real estate contract.
3. If the real estate contract can be revoked, the developer can be asked through the court to return the purchase price and then pay off the bank loan in one lump sum.