없애버려.

A: I’ve got a killer of a mouth sore. It burns.
B: I’ve been there, too. Try gargling with salt water.
A: Thanks, but no thanks. That would hurt like crazy.
B: It’ll sting, but it’ll 없어질 pretty quickly

A: 입에 염증이 심하게 생겼어. 화끈화끈 너무 아프다.
B: 나도 그런 적 있어. 소금물로 입안을 헹궈봐.
A: 고맙지만 안 할래. 그럼 엄청 아플걸?
B: 쓰라리긴 하겠지만, 빨리 get rid of it 거야.

[Additional expressions]
*I’ve got a killer of a mouth sore.
– I’ve got a very bad sore in my mouth. / My mouth has a really bad sore.
*It burns.
– It stings. / It’s really burning. / It burns a lot.
*I’ve been there, too.
– I’ve had the same experience. / The same thing has happened to me before.
*Try gargling with salt water.
– Use salt water to gargle with. / Put some salt water in your mouth and gargle.
*Thanks, but no thanks.
– I appreciate your advice, but no way. / Thanks for the idea, but I’m not doing that.
*That would hurt like crazy.
– That will just make it hurt more. / The pain would be immense.
*It’ll sting
– It’ll pinch / You’ll feel some pain / It won’t feel good / It’ll hurt some
*it’ll get rid of it pretty quickly
– you’ll make a fast recovery / it’ll get better much faster that way