I have placement of my niece and nephew. I have had my niece for 2 years now parents have supervised visitation they have not been here to see her can I have abandament against them? And have not seen there son in 7 months what can I do to have rights taken away I'm looking on down the road to adopt them both

You don't "get them taken away" they will retain them unless the court determines them to be a threat to their safety. The courts rarely do this absent an actual adoption.

Their rights would be terminated concurrent to and as part of the adoption process.

The only thing you can do is file for adoption. You cannot use abandonment, except as grounds to get the adoption granted over their objections. You cannot get their rights terminated except as part of an adoption.

So you need to wait until you can file for adoption or push that up.