you would open the common1.cns in the data folder.
copy the states that have what you want to disable.
and paste them within your characters CNS file.
you don't need to copy the entire thing, or even the file, just the parts you need.
then if you look at state 53 i think, in the common1.cns it has "Jump Down" which is unused. but basically you can see how to "null" out a state so it doesnt work.
and do that for the ones you want to disable.
DO NOT EDIT YOUR COMMON1.CNS IN YOUR DATA FOLDER.
THAT WILL AFFECT YOUR ENTIRE MUGEN.