Hi, it's Annabelle.
I have these recordings of my voice with some music, but when I solo just my voice, even when the microphone is in cardioid during recording, unfortunately there's the hum of my refrigerator. How do I get rid of that hum? Does Sonar 8.5 Producer have a denoise tool? If so, where do I find it?

There is no noise removal tool bundled with SONAR 8.5. There presets in Sonitus EQ for 50 and 60 Hz hum removal.

I would rerecord  your voice with the refrigerator off. If that can't be done try any number of noise reduction plugins on the market. Also a gate may prove useful.  
 
I like soundsoap. Sound Forge has a suite of noise reduction tools. Izotope has RX a very good noise reduction app. 

You could try recording just the hum, to phase invert it against the vocal track?

John
I would rerecord  your voice with the refrigerator off. If that can't be done try any number of noise reduction plugins on the market. Also a gate may prove useful.  
 
I like soundsoap. Sound Forge has a suite of noise reduction tools. Izotope has RX a very good noise reduction app. 

+1 on John's comment, I turn my frig off and even if it's twenty below, I'll turn the furnace off (keeping the wood stove on), etc
 
++1 on Soundsoap, I use it primarily on podcasts with wind and bad recording, etc. but it has regular upgrades and is becoming quite a powerful and easy to use tool!