How to deal cells with same content except on

Hello,
hey i got lots of data in the B collum a lot of the data is the same, repeated in row after row but not all data is the same. waht i have tried to figure out how to do for a long time is: how do i delete all the cells that contain the same data except one. i will give an exempel:

abc
abc
abc
cba
cba
cba
dac
dac
dac

is gonna end up looking like this :

abc

cba

dac

hope this is understandable

thanks for any help
(sorry for bad language typos etc)