How to remove background noise in FMOD Stuido?

How can I remove background noise from an audio file in the FMOD Studio app?

That’s really not the purpose of FMOD Studio to do this kind of things at runtime. You should do this in an audio editor and reimport the file in FMOD Studio.
The filters to apply will depend on the type of noise, but an EQ would probably be the first thing to look at.