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)