or.....
=SUBSTITUTE(SUBSTITUTE(A1,"[","",2),"]","",2)
Firstly you need the input to be consistent.
Substitutes new_text for old_text in a text string using the format: SUBSTITUTE(text,old_text,new_text,instance_num)
=SUBSTITUTE(SUBSTITUTE(A1,"[","",2),"]","",2)
SUBSTITUTE(A1,"[","",2) Looks...