You can usually repay the loan early according to the contract terms, but don't calculate the amount yourself by adding up the remaining installments.
Key points
Request an "early settlement number" from the bank for a specific date that includes the principal amount and any applicable early repayment fees or charges.
Compare this number to the cost of keeping the loan until the end of the term, and after making the payment, ensure you receive a clearance certificate and close the facility.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.