This usage could be anywhere on the system outside of the user's home directory. I suggest running the following commands to obtain the location of all files owned by this user:
Replace the first command with the actual username of the account. This will output the account's UID. You can then replace "UIDNUMBER" in the second command with the actual UID of the account. The results will be output to /root/username.output which you can view after the command finishes.
# id username
# find / -uid UIDNUMBER > /root/username.output