Tenant Lease Ended, Did not Vacate. What to do?

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Great news! I close on my first property (duplex) on Tuesday, but have encountered the first obstacle. 

The seller provided notice to the tenants that the lease would end June 30. Unfortunately, they are still in the property and from driving by, it doesn't look like they plan to leave any time soon. Wisconsin Statute 704.23 simply states that I can "proceed in any manner permitted by law to remove the tenant and recover damages." That is pretty vague, so I'm wondering what I can do? Does that mean proceed with the eviction process? Does that mean that I can contact the sheriff and have them removed? 

Rehab is scheduled to start next week with an open house the following weekend. I'm on a tight timeline and trying to figure out how to mitigate this issue.

I know I can try cash for keys, but need to know what my next step is.

Thanks in advance!