1. If you want to directly convert it into RMB, you must go to China Bank to exchange it. The bank will convert it into RMB at the "cash buying price" according to the foreign exchange rate of the day.
2. If you want to change it into other foreign currencies in circulation, you can go to Bank of China or other banks that provide foreign currency exchange and directly change it into other foreign currencies in circulation!
Of course, other banks can also indirectly convert your foreign currency into RMB, but it is more troublesome. You need to open an account and deposit foreign currency first, and then handle the "foreign exchange settlement" business for you, so I suggest that if you want to change it into RMB, you can go directly to "China Bank".
4. Many banks can handle it, and China Bank is the only one that can directly convert the foreign currency in circulation into RMB! Others, such as ICBC, Bank of Communications and China Merchants Bank, can be handled indirectly and belong to the business of "settlement of foreign exchange". Of course, many foreign exchange banks can directly convert one foreign currency into another!