check and delete row data from adding data on another table

[Mattleft]

I'm trying to build and farm data app and maybe it's a very silly problem, but I'm stuck with it. I have a table where i can add every new mum that we have in a herd (other table), and I need if possible that they can recognize this new data (same cow number in two table) and delete the row (herd table), leaving me with no cow numbers repetitions.

Appreciate the help 

Thanks