Delete duplications in row not column

Hope someone can help, I'm trying to work out a macro or some code that will delete duplicate entries in the row not column.

example:

Cell A Cell B Cell C Cell D
1 YU2 ABH YU2 ABH YU2 ABH YU2 ABH
2 abc 123 yorkshire boston abc123
3 blean kent york dge 098
4

I want for instance cell D to retain the post code entry and the other entries to delete if they contain the same post code, else leave entry if value is different.

Hope you can help. Thanks