yes, it's possible...
commands are defined in the .cmd file inside said char folder.
however based on your questionI guess your mugen knowledge is nearly zero, so I recommend to read some tutorial about commands before messing with something..
here's some extra help though:
-open your char folder (the one whose special you want to remmap)
-open the file wit extension .cmd with notepad
-look for something like:
[Command]
name = "insert name"
command = ~D, DF, F, D, DB, B, U, B, y <-----this is what you are looking for
time = xx
or
[Command]
name = "insert name"
command = ~D, F, D, B, U, B, y <-----this is what you are looking for
time = xx
and change the "command" line from
command = ~D, F, D, B, U, B, y
to
command = ~D, B, D, B, y
if the move has a name is easier to identify and locate it
