Options to remove/Increase Rent

[Timothy Burns]

Hi all, I have a pending offer on a duplex in an A neighborhood area with good rents, that I will be house hacking. 

There is a long term tenant since 2006 who is now month to month and pays well under market rate. 

What are my options on increasing the rent/removing tenant that are within the bounds of law? 

Do I have the option to create a brand new lease on my own or do I have to use the old one? 

Is there anyone in the KC area that can reccomend a good landlord lawyer?