Webmail User Guide
SyncML Devices
Options > Advanced > SyncML Devices

This options allows you to delete the SyncML server cache data for a client device that has previously synced with the server.

Note: If the cache data is removed for a specific device then please be aware that if the device re-syncs it is possible that duplicate entries may occur on the mobile device or within web mail. Only delete the cache data if you are sure.