Does the individual pay the social security unit to renew the insurance?

You have to go to the bank to stop paying social security, and then the unit can pay you.

According to the relevant provisions of the transfer of social security procedures from individuals to units:

If an individual insured person is employed by an employer, he/she shall go to the original insurance agent to go through the formalities of reducing the payment with the roster of registered employees issued by the employer.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.