what't the right way to collect unpaid last month Rent

[Ostany D Isaac]

My Tenants are moving out on February 1st of this year and have decided not to pay the last month rent :(since they already moving out, should I still do a 14 days notice to quit? or a small claim would do it? since I have a time constraint, I wanted to do it as efficient as possible, thank you for your help in advance :)