I have made that too
The key point is select-> color range ->red
It can select a whole range of red
and delete the red
When you know the precise RGB value of the replacement colour, then Image > Adjust > Replace colour is as clean and straight forward a way as any. If you don't know the RGB value, but have another image where the dominant colour is what you are looking for, then Image > Adjust > Match colour is a nice easy way to go, but lacks the precision of Replace Colour.