It definitely is not extortion. This is purely a civil matter. The police will not get involved. Since you were renting from him, legally his position is that of a landlord to you. If you have not paid all the rent, he can serve you with a three day notice to quit or pay all the rent. If he agreed, even just orally, that you could pay half the rent now and half 9/3 [why have you not given us what the current situation is?], then he can not give you a three day notice. He can give you a 30 day notice that he will not rent to you again 30 days from the date of the notice. He would then have to file an unlawful detainer action in court against you in order to get a court order of eviction.
Answered on Sep 26th, 2016 at 6:45 PM