How do I get steamrep reports removed if they're invalid?

You can't/don't.
We do not remove reports once submitted regardless of outcome. The reports someone makes are serious and treated as such with transparency towards the reporter/Op and the user being reported.
I've changed the most recent report against you as DECLINED as our prefixes have changed and I will add an additional note that you were not found guilty of any wrong doing per policy at the end of that response.
Best I can offer.

The others are still invalid per policy and noted as such.