I’m surprised that you didn’t make “convey vacant” a condition of the purchase agreement, since you knew the previous owner was still living there.
Since you accepted the property with a tenant – which is what the previous owner now is – you must follow your jurisdiction’s laws to terminate his at-will tenancy. In my state, that means at least 30 days written notice. I was recently informed that there is a federal law covering foreclosures that may require up to 90 days notice, but I haven’t checked that out yet.
You must make sure the notices are properly served (my state requires all notices to be served by licensed process servers) and all timelines adhered to very strictly (if it says 30 days, it doesn’t mean 29 1/2 days). If the tenant fails to leave, then you evict just as you would any other holdover tenant.
Contact an eviction service or a real estate attorney licensed where the property is located to guide you through this. Don’t try to do it yourself because even one slip-up can cause you have to start all over again, which can open you to charges of harassment by the tenant.
