You will find the answer in the hadith of Jabir, may Allah be pleased with him, who said: "The Messenger of Allah cursed the one who consumes riba (interest or usury), the one who gives it, the one who writes it down and the one who witnesses it. He said: 'All of them are equal in sin.'" (Reported by Muslim, may Allah have mercy on him, in his Saheeh, no. 1598)
Commenting on this hadith, al-Nawawi, may Allah have mercy on him, said: This is clearly a prohibition of the writing down or witnessing of a contract between the two parties involved in a riba-based deal. It also includes a prohibition of helping others to commit wrong acts. And Allah knows best.
It is inevitable that the employee in a riba-based bank will play a part in riba dealings one way or another, even if he is just a security guard. Maybe Allah will help you, my brother, if you are patient, to find halal employment. (Interpretation of the meaning) " And whosoever fears Allah and keeps his duty to Him, He will make a way for him to get out (from every difficulty)." [Al-Talaq 65:2]