Here 치다 means "to suppose, assume, presume "
다(고) 치다 means "suppose that"
비행기를 탄다고 쳐도 내일까지는 못 간다
I couldn't get there by tomorrow even if I were to fly[go by plane].
Suppose I go by plane. I wouldn't be able to get there by tomorrow.
그것은 그렇다 치고, 이제 일정에 대해 얘기해 봅시다
OK then[Let's leave it at that]. Now let's talk about the schedule.
수영장에 갔다 치고 샤워나 해야겠습니다.
Supposing that I came to swimming pool, I will just take a shower.
열명 정도 온다 치고 식사 준비를 하십시오.
Supposing that ten people will come here, prepare a meal, please.