Is it possible to archive table rows of an RDS read replica?
A read replica is basically a read_only slave in normal MySQL speak. RDS does allow you to change the read_only parameter, so you can purge the records you want and RDS won't recopy the data from the master.

However be careful if you go this route. If you run DML statements on the master for rows that don't exist on the slave, you likely will break the replica. If replication breaks, you're only choice is to drop the replica and create a new one from the master. You'd then have to re-purge the rows.

I am curious why you want to remove data from the replicas for report queries. I would expect reports would want more data, not less, than the master.