Moving back into a rental. How to evict tenants?

[Alejandro Arciniega]

I have a property I've been renting out for the last 5 years. I currently have great tenants in place but I make sense for my wife and I to move back to the property to start our family. We are expecting our first child in mid July and want to get into the property by April 1st to start some remodels before the baby comes. I've communicate this to the tenants and they are understandably sad as they would rather stay but are understanding of the situation. I've essentially given them a 90 day notice via text but would like some advice on the situation. Do I need to formally serve them with 60 day eviction letter? We have a good line of communication and I don't see them not vacating on April 1st but would it be unwise to take their word for it?  Thanks for you guys input.