"There is no bathroom here."
i wrote 这儿不在洗手间 and i wonder if it is correct.
这儿不在洗手间 = here is not at the washroom
So, sorry, doesn’t quite mean what you want it to.
It’s possible that 这儿不是在洗手间 might be understood but I think it still sounds a bit odd. Might be better without the 在，but you’re still missing “There is”.
Translating “There is” you really need 有。I think.