Do not put his stuff on the lawn. You need to serve a three day notice to quit the property, pursuant to Code of Civil Procedure section 1161a, subdivision (b)(4). If the seller does not move out with the three (3) day notice, you will have to bring an unlawful detainer action against him.
It does not sound as though the property is covered by the Los Angeles Rent Stabilization Ordinance (LARSO), because it is a single family residence.
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