dozorca, woźny, nadzorca (budynku)
Being a janitor is a good job if you're a writer.
I got a job at the medical center, practically a janitor.
Your father was a janitor, his son's only a cop.
The caretaker told us nobody came in or out.
At this hour, you will find only the caretaker in this building.
At this time, the only person in the school is the caretaker.