You must disable the cabinet first.
LD 32 DISS x where x is cabinet 1, 2, etc. whichever you need to disable.
Next in LD 135 DIS FIL x where x is the Fiber link to that same cabinet. DIS FIL 1, DIS FIL 2, etc.
You can STAT FIL in LD 135 to find which Fiber links are in service. They work in pairs 1 & 3 and 2 & 4. If you have a dual port Fiber Daughterboard but only Expansion cabinet 1 is equipped FIL 3 will show disabled. Exception is if you have Single port Fiber daughterboards but then you can only have 2 Expansion cabinets.
Once those steps are done the cabinet and Fiber Link are both down.
To enable it's ENLS x in LD 32 and ENL FIL x in LD 135.