In cash is the correct usage.

1. When paying in cash, you cannot use by cash, you can only use in cash, and in spoken language, in can sometimes be omitted.

For example: I would appreciate it if you paid in cash.? If you paid in cash, I would be very grateful.

For example: David paid cash for the newspaper. David bought the newspaper with cash.

2. By payment method, indicating how to pay. Common communication methods include credit card and check, etc.

For example: It is very convenient to pay by credit card. Pay with credit card Very convenient.

For example: I have no cash with me, may I pay by check? I don’t have cash with me, can I pay by check?

1. cash: British [k?] American [k?]

n. Cash; (any form) money, funds;

vt. Cash a check;

cash, coin, coinage, currency, money, and specie all mean "money, currency". The difference is:

1. Money originally referred to coins made of metal, and now banknotes are also included; cash refers to "cash, cash". For example:

The shop doesn't accept checks; it wants cash. The shop doesn't accept checks, only cash.

2.coin, coinage, specie all refer to "coins", and coin mainly refers to "gold coins, silver coins". For example:

This is a kind of gold coin. Coinage mainly refers to "currency system". For example:

What sort of coinage do they use in Britain? What currency system is used in Britain?

Specie emphasizes "coin payment". For example:

Payments were demanded in specie. Payments were usually required in coins.

3. Currency refers to the currency currently circulating in the market of a country or a region. For example:

Which currency is among the strongest in the world? Which currency is the most valuable in the world?