Sometimes it is necessary to unprep a Forest,you might have made a spelling mistake for example. You cannot use the OCS setup utilty to do the Unprep. You must use the command line. It is relatively easy and I have done it myself with great success.
Microsoft have a document which details all the command line options and can be found at the link below. This link has numerous other OCS documents that can be downloaded and it is well worth doing so if you are implementing OCS 2007 R2.
http://www.microsoft.com/downloads/details.aspx?familyid=E9F86F96-AA09-4DCA-9088-F64B4F01C703&displaylang=en
The syntax, taken from the Microsft documentation is as follows :
Unprepping a Forest removes prior Office Communications Server forest preparations such as objects, containers, and extended property rights.
The following command runs the ForestUnprep action. LCSCmd.exe /Forest[:
] /Action:ForestUnprep
Such as: LCSCmd.exe /Forest:contoso.com /Action:ForestUnprep
By default, ForestUnprep will not proceed if any previously prepared child domains exist on the forest root.
However, you can use the /Force switch to make ForestUnprep proceed; this causes all deployed Office Communications Servers to stop functioning.
Use the following syntax and parameters to force a ForestUnprep action. LCSCmd.exe /Forest[:] /Action:ForestUnprep [/Force[:{TRUE|FALSE}]] Such as: LCSCmd.exe /Forest:contoso.com /Action:ForestUnprep /Force Hope that helps.
