Need to delete Duplicate active cell in ROW (ROOM or Subject)

Hello,
Thanks lot your Interest about my Problem and also appreciate your support.

I have excel sheet I need to prevent duplicate entry on SUB or ROOM in one ROW.

As example after I enter RM# as 1 in E4, This need to stop pick the room 1 in entire Row, also I link through data Validation .

if Some one pick the RM# 1 in Cell Q1, That Cell need to delete by popping up Error of " Entering Duplicate value not allowed"


also need to do same for Subject ("SUB" )as well.

Best regard

Indika