PHP Code:
SYSTEM                         SYSTEM                             819200
R000                           SYSTEM                            1064960
RBS01                          RBS                              11714560
RBS02                          RBS                              11714560
RBS03                          RBS                              11714560
RBS04                          RBS                              11714560
RBS05                          RBS                              11714560
RBS06                          RBS                              11714560
RBS07                          RBS                              11714560
RBS08                          RBS                              10649600
RBS09                          RBS                              11714560
RBS10                          RBS                              11714560
RBS11                          RBS                              11714560
RBS12                          RBS                              11714560
RBS13                          RBS                              11714560
RBS14                          RBS                              11714560
RBS15                          RBS                              11714560
RBS16                          RBS                              11714560
RBS17                          RBS                              10649600
RBS18                          RBS                              11714560
RBS19                          RBS                              11714560
RBS20                          RBS                              11714560
RBSBIG                         RBS                              15728640 
So I offline the rb segments the drop the RBS tablespace including contents.

What should be done with the 2 system RBS's ?

So far I have not seen in any Oracle doc a recommended process steps for converting from RB to UNDO.