I missded the change to column C, how often do you need to modify column C because a formula approach is frought but teylyn has the general idea if only occasional but you will need to set column E with:
=SUBSTITUTE(C2,"[" & D 2 & "]","")
and copy columns D and E and use paste special into columns C & D because the formula cannot then maintain the column D vallue once column C is modified.
Chris