If avast can detect it and gave you a warning what action did you choose, move to chest, delete, what?
What happened upon carrying out that action? - I suspect you got a permissions/protection error of some sort otherwise it wouldn’t be in the recycle bin to empty.
You could try the, schedule boot-time scan in avast’s menu (or try the ‘Schedule Boot-Time Scan’ using RejZoR’s AEC avast! External Control Tool