What is the ruling on my working in a job that requires dealing with commercial insurance companies and issuing payroll statements for employees who desire usurious loans, knowing the impermissibility of these transactions?

It is forbidden for a Muslim to aid in what is unlawful, due to the Almighty's saying: "And do not cooperate in sin and aggression." Therefore, it is impermissible for an employee to assist in prohibited commercial insurance contracts or usurious loans if he knows that the person requesting salary statements intends them for that unlawful purpose. For everything that is intended for the unlawful or leads to disobedience is forbidden. If you can avoid such actions, then you may remain in your job; otherwise, no.