Clear all page level skins in a Portal:

update {databaseOwner}{objectQualifier}Tabs

set skinsrc=null

where SkinSrc is not null

and PortalID=0

Clear all page level containers in a Portal:

update {databaseOwner}{objectQualifier}tabs

set containersrc=null

where containersrc is not null

and PortalID=0

Clear all module level containers in a Portal:

update {databaseOwner}{objectQualifier}TabModules

set ContainerSrc = null

where TabModuleID in (select TabModuleId

   from {databaseOwner}{objectQualifier}TabModules tm

   join {databaseOwner}{objectQualifier}Modules m

           on (tm.ModuleID = m.ModuleID)

   where ContainerSrc is not null

   and m.PortalId=0)