Policy
At logoff, delete local copy of user’s offline files
Deletes local copies of the user's offline files when the user logs off. This setting specifies that automatically and manually cached offline files are retained only while the user is logged on to the computer. When the user logs off, the system deletes all local copies of offline files. If you disable this setting or do not configure it, automatically and manually cached copies are retained on the user's computer for later offline use. Caution: Files are not synchronized before they are deleted. Any changes to local files since the last synchronization are lost.
a6182d80c653 Pol_PurgeAtLogoff Registry
Copy registry mappings
HKLM\Software\Policies\Microsoft\Windows\NetCache\PurgeOnlyAutoCacheAtLogoff Policy notes
Deletes local copies of the user's offline files when the user logs off. This setting specifies that automatically and manually cached offline files are retained only while the user is logged on to the computer. When the user logs off, the system deletes all local copies of offline files. If you disable this setting or do not configure it, automatically and manually cached copies are retained on the user's computer for later offline use. Caution: Files are not synchronized before they are deleted. Any changes to local files since the last synchronization are lost.