I know you think that this is distinct from your other issues with the estate and sale of the property, but you shouldn't really scatter your problem across multiple threads. It impedes people from having a big enough picture to answer the question.
Again, you're going to have to indicate what state this is.
As Q points out, the question is not if you can fire the broker, but whether they are still entitled to the commission when the property eventually sells.
If this agent works for a brokerage, you may wish to contact the brokerage with your concerns. (Note "Realtor" is not a generic term for agent. It's a trademarked term for an agent who is a member of the National Association of Realtors.
It's hard to tell based on your vague statements. Notes to inspectors really don't mean much of anything. If they e-signed documents without authority, then whoever's name was "signed" to the document will have course of action. As for strikethroughs, such is not uncommon with the preprinted forms. It's obligatory for those who sign contracts to understand what they're signing no matter how obfuscatory they may appear. If the strikeouts were done after the fact, then you may have serious issues.
Since both you and the other heir here seem to have retained counsel, you should be talking to your lawyer(s) and possibly to the estate attorney as well.
