SIP -ELSS lock in period

ELSS comes with 3 years lock in period. In case of SIP, does every single SIP - monthly can be withdrawn only after three year (i.e if i make a SIP on 1 january 2017 and second on 1st feb 2017 and so on, i will be able to withdraw my first SIP on 1st jan 2021 ane 1st feb 2021 and so on ) or entire sum that is accumulated at the end of three years can be withdrawn???

Each SIP installment will have a lock in period of 3 years. So you can redeem only those units of ELSS funds which you have been holding for 3 or more years.