Existing Tenants Living in Prospective Purchase Property

Hello to all you landlords out there!

I have a question regarding tenant / housing laws in King County. I am interested in buying a 3 unit multifamily property in Renton, WA. It'll be my first property purchase ever and I plan to live in one unit (to be in compliance with FHA regulations) and rent the others. I don't live in WA yet so I am not familiar with the tenant laws in the region. For those of you who are familiar, what might the process look like evicting an existing tenant so that I can move into the unit? Will I run into issues since the tenant likely hasn't done anything wrong to validate grounds for the eviction? Any light you could shed on the subject would be much appreciated. Thanks for your help!!