Reference: 7110.65 3-10-5
PHRASEOLOGY-
RUNWAY (number) CLEARED TO LAND.
A go-around may be initiated either by the pilot or the controller whenever they feel that is the safer option compared to continuing the approach. The sooner you recognize an issue, the better. Telling a pilot to go-around earlier is safer for them and gives you more space to direct them to avoid other aircraft, like a preceding departure.
Coordinate missed approaches with P80. If you don't immediately send them back to Approach, either give them a heading and altitude, or instruct them to fly the published missed approach.
As the Local controller, it is your job to ensure safety on your runway(s). You should always be paying attention to what aircraft are inbound and developing your plan for sequencing departures. Coordinate with the approach controller if different spacing is needed for arrivals.Â