(.*) COs?[(.*)|[.*]|{.*}|''.*''|".*"](.*)

s/(.*) COs?[(.*)|[.*]|{.*}|''.*''|".*"](.*)/$1 CO $2

3M CO 'A'(MINNESOTA MINING AND MANUFACTURING COMPANY)

3M CO A'(MINNESOTA MINING AND MANUFACTURING COMPANY)

(.+?)s+COs+(['"].+?['"])([([{]).+?([)]}])

(.+?) # anything before Co;
(['"].+?['"]) # the quotation part; and
([([{]).+?([)]}]) # inside brackets included bracket, which we can use escape if required.