Definition of janitor:

one who keeps the premises of a building (such as an apartment or office) clean, tends the heating system, and makes minor repairs

https://www.merriam-webster.com/dictionary/janitor

a person employed to take care of a large building, such as a school, and who deals with the cleaning, repairs, etc.

Or

a person whose job is to clean and take care of a building

https://dictionary.cambridge.org/dictionary/english/janitor