What should we do with translations that are in the wrong language?
You are Premium member, so you can edit hints if you notice errors. If you click on the blue "Edit" button above the popular translation you will be able to change the flag and move hint into correct language.
In case that translation is wrong and you don't know which language it is, you can remove it, yes.
I can't test this now as if I click edit nothing happens. But I've never seen any flag to change one wrong translation to a different language. The only thing I saw it's a button that doesn't eliminate the wrong translation but just change with the number zero: translation (0).
Yes, changing it to 0 will do the job for now.