When unregistering a feature dataset (FDS) as versioned, if the FDS contains a topology, a dialog box appears indicating that the topology contains edits which haven't been compressed.
This is a known issue that is currently being addressed.
Ensure that all edits have been reconciled / posted and compressed depending on the version structure.
The Unregister As Versioned dialog box should only list the topology when expanding the FDS tree in the dialog box for the feature dataset.
If there are other feature classes listed within the FDS, then there are other edits on those feature classes that need to be compressed. Cancel the operation and compress those outstanding edits before continuing.
New at 9.2: if the edits are only on the default version, check the box for 'Compress all edits in the default version into the base table' and continue. If there are outstanding edits in other versions, cancel the operation and reconcile/post and compress those edits. A warning message indicates that all edits to versions will be lost if the operation is continued.
Assuming that the topology is the only item listed in the FDS tree, click continue to proceed with the unregister as versioned.
For version 9.2, select either to check the box or leave it unchecked; the end result is the same on the topology.