6 year old Rhode Island still laying?

[Crash812]

I have a 6YO Rhode Island Red, a 4YO Black Australorp, and 2YO Plymouth Rock. We are getting two eggs per day fairly regularly. The Australorp's comb in not bright like the others, so I am assuming she is not laying. We are getting one large egg and one medium-small egg. The RIR seemed to always give us larger eggs, and I can't say I know for certain, but the Plymouth gave smaller ones, since we never had smaller one prior to getting her. We have four new chicks in the brooder, and need to get rid of two of the older, since our HOA allows for only 5 birds, and we really don't have the room. Thoughts on who to get rid of? The RIR is the top bird in the flock.

 

[ChickenCanoe]

You can easily figure this out.
https://www.backyardchickens.com/ar...o-is-not-butt-check.73309/#ams-comment-508695
Don't necessarily trust the comb color and don't necessarily think a 6+ year old hen can't be productive.