If there is a previous translation, then select it, and use the reverse to previous. Otherwise, select "edit" and try to fix it if you can, if not, just leave a comment for the next translator what need to be fixed.
First I tried reverting to mine to erase it. But it just kept coming back like a bad penny. So, finally I wrote on the stream of the correct translator and got a very kind reply. Thanking you again for your help.