OPTION #1 - 谢谢 - 不谢 OPTION #2 - 谢谢 - 不用谢 Both of them are correct. The second one is much formal and polite. If you want to be gentler, I think 不用谢 is better.

No.2

Both of the options are correct, the first is casual in informal condition, we usually use "谢谢！不客气” as formal type

Las dos son correcto.

both are correct, the second is more polite