How to discontinue lease with section 8 tenant

[Padma Mody]

I bought the single family house two months ago which was rented with section 8 tenant. Last week I received the letter from section 8 to repair 4 items. 3 items are easy to fix but they ask us to fix HVAC - not cooling whole house... During the inspection, I found out that house need to fix HVAC and also some drip behind the wall between kitchen and bathroom. HVAC is between bathroom & Kitchen wall on hallway. For HVAC cooling problem, I am going to call HVAC guy and if he will tells me to change the whole entire HVAC, I prefer to do all renovation at one time.

Yesterday, I find out that the lease is month to month. Other thing is that, the rent is only $685 for 3BR and 1.5 bath. Which is very low compare to other house in the same area. And I know that tenant can't afford to pay more rent if I raise the rent. With tenant, I can't do the major repair in this house. And after renovation, I like to get more money! 

Can I just tell my tenant that I am not going to continue her lease? How many days of notice I should give to her? For month to month lease, how many days of notice is required?