reo occupied with lease

[Ramsey Vanlandingham]

Hi im ramsey. I currently have signed a psa to purchase a reo home that i plan on occupying.  This home is currently occupied. The property is in Missouri. I received the title commitment today and it says the Tennant has a five year lease signed Jan 14 . this document is recorded in the deedsnoffice. My question is do I have to let her live out her lease of a unrealistically low 275 a month lease for the remainder of her term or can I evict her once the deed is re orded in my name.  I hear many different things in response to this. Such as I only have to give a ten day notice, I also here that I can give her ninety day notice, I also heard that I avide by her lease.  I need help..