Former employee reviews can be taken down.
Posting negative reviews about a current or former employment experience is no longer allowed on Google My Business. (Google Review Policy)
Let me explain, Google my business has policies in place that determine what types of reviews can be left. I’ll be honest its not easy to fully understand them and it often easier to see what happens rather than trying to work out what they mean.
As such, recently Google amended its policies, and should a former employee leave a review on your Google My Business you are able to contact Google My Business to have it taken down.
This is good news, since there is a clear conflict of interest. So, if you have a review from a former employee and would like it removed, just contact Google My Business.