Need advice about getting rid of inherited month to month tenant

[Caren Klein]

So we just closed on a property and inherited tenants, the previous owner had them on month to month with no security deposit.  We are putting the tenants on leases. One of the tenants has got to go. We know that we have to give the tenant a letter saying that we are not offering them a lease. We also know that as long as we deliver the letter by the end of the month, they will have the entire next month to leave. My question is, to be legally compliant, how does the letter need to be worded, what particulars need to be included, and does it have to be sent registered or certified?