Put this formula in B1:
=LEFT(A1,FIND("(",A1)-1)
This one in C1
=RIGHT(A1,LEN(A1)-FIND("(",A1)+1)
Satisfied?
Select columns B&C, do copy --> PasteSpecial Values
Delete column A
Colmun B becomes A
C becomes B
This is the only way to do it if not using VBA.