When you restore file a copy remain in chest, just in case
So you have to check that they are back at there location, when all is OK you may delete

Use the Virus Chest >> https://www.avast.com/faq.php?article=AVKB21#artTitle

Video >> https://www.avast.com/faq.php?article=AVKB149#artTitle

What happens to the files if i re-install Avast?
If you uninstall avast, files in chest are gone