I want to evict a current tenant living in my rental house so I can sell the house.

My husband passed away June of 2020. We have owned a 2 unit house since 2008 in Petersburg Mich which he rented out. I am trying to sell the house because I am not able to take on the tasks involved with being a landlord: I talked to both tenants about this a number of months ago and the couple in the lower unit moved out. The woman in the upper unit says she is trying to find a place but she does not seem to be interested in leaving although I tried to provide financial incentives for her to do so. The realtor says she will have trouble selling the house with her living there. I told her I am going to send her official notice to vacate but I would like to make sure I am proceeding legally.