Portland Oregon Multnomah Co

[Eva Splichalova]

I have rented room in my house to friend, she has been living in my house (I own) for over a year. She signed month to month rental agreement in April 2019. It has not been working out lately, and I asked her to move out. I am afraid she will be prolonging her stay. How long do I have to give her to move out? Is it 30 days as per agreement or is it 60 days because she lived here over a year?  Can the notice be posted on her bedroom door or is it better to send it via US mail? Portland and Multnomah county has confusing laws on this. Thank you for your help!