Unenrolling and clearing the data shown


I have a question about re-assigning machines and unenrolling. When we get a machine back we unenroll it and assign it to a new user. Sometimes the machine will sit there for a few weeks or so. During that time the data that it had before it was wiped shows up. For example, we have a policy that checks if the machine needs updates. Well, since the machine is not being used and not enrolled, it's looking at the old version which was on it before and adds it to the count of machines that need updates. Is there a way to fix this or maybe I'm just not doing the process correct to unenroll or wipe machines. Thanks!