If you have the appropriate privileges you can roll back and demote in the same operation.
When you demote an object, it is automatically rolled back from default areas at higher stages. If you have privileges that allow you to demote an object, you are implicitly granted deployment privileges that allow you to perform the rollback. If the rollback cannot be performed demotion will still proceed. Be aware that rollback and demotion are independent transactions. The demotion will occur immediately, but the rollback will be queued and may not succeed.
If the object has been deployed to manual areas at a higher stage you must roll back these deployments before performing the demotion. The object will not be demoted if it is deployed to manual areas at higher stages. Rolling back from manual areas requires deployment privileges.
If you have deployment privileges for an area, you can manually roll back any deployment as long as the area version created by that deployment is not depended on by later area versions.