I have "terminated" Month-Month leases and "Not Renewed" expiring leases for just this reason. I had a 3-way war between tenants and all 3 eventually were sent on their way. I also used some leverage in unpaid rent, deposits etc... as a reason to begin evictions to get them out sooner.
I have since added to my leases that any harassment of other tenants be it verbal, written, or unsubstantiated allegations would be considered a breech of the lease terms and eviction proceeding started.
If she is getting close to end of her lease; I would notify her that you are choosing not to renew the lease and then wait it out....that is the cleanest way; however, look at your leases very close and try to find something that you could hang your hat on as a lease breech. I would also notify her in writting to stop these unsubstantiated allegations.
Be very careful as well......she may be perfectly fine and the person complaining to you MIGHT be the culprit. There are some master manipulators out there that can spin a very convicing story.