Hello,
I'm affraid it's bug in current version. In query Proc_CMS_User_RemoveDependences there is strictly specified DB owner of [CMS_Document] table to dbo by mistake, while you are probably using another one. Please go to Microsoft SQL Server Management Studio, in ObjectExplorer expand your site database node, then expand Programmability -> Stored Procedures sub-node. Find the Proc_CMS_User_RemoveDependences procedure, right-click on it and choose modify. In procedure query replace this part of code:

UPDATE [dbo].[CMS_Document] SET DocumentCreatedByUserID=NULL WHERE DocumentCreatedByUserID=@ID;
UPDATE [dbo].[CMS_Document] SET DocumentCheckedOutByUserID=NULL WHERE DocumentCheckedOutByUserID=@ID;
UPDATE [dbo].[CMS_Document] SET DocumentModifiedByUserID=NULL WHERE DocumentModifiedByUserID=@ID;

with this:

UPDATE [CMS_Document] SET DocumentCreatedByUserID=NULL WHERE DocumentCreatedByUserID=@ID;
UPDATE [CMS_Document] SET DocumentCheckedOutByUserID=NULL WHERE DocumentCheckedOutByUserID=@ID;
UPDATE [CMS_Document] SET DocumentModifiedByUserID=NULL WHERE

and execute query.

This will be fixed in 2.1b version.

Best Regards,

Martin Dobsicek