You can make part-prepayments towards your loan account in the form of cheque payments. If you have savings account with the same bank you can give a standing instruction. SBI usually asks loan account holders to start a savings account with their bank for easy money transfers towards the loan EMI. You can transfer the amount you wish to pre-close to your SBI savings account and issue a cheque of that account against your loan account or give standing instruction from your savings account towards the loan account. SBI will not take any penalty / charges for loan pre-payment / closure.

Once your cheque is realized / amount is credited in your loan account, you can approach the bank for restructuring your EMI. Most banks consider restructuring of loan tenure (reducing loan tenure) over restructuring of EMI in case of part-prepayment. But you can make a special request at the branch to consider revising EMI.