Don't stab your co-creators in the back. It doesn't look good.
However, for whatever reason (generally fear), it happens. You hire someone to do a job, don't like what they're doing for some reason, and instead of telling them, you stop communicating with them and hire someone else to do the job. Or worse, you go behind their back and ask someone to look over their work to make sure it's up to snuff.
I was contacted by a creator who had hired an editor and said that they came highly recommended. They then contacted me and wanted my opinion on some things concerning the work being done, but they didn't tell the person they hired that their work was being gone over by someone else.
For the record, I'm not in the habit of checking someone else's editorial work. Not like that. I declined the “work.”
Either you trust the person you hired, or you don't. Hiring mistakes are always being made. It happens. Be adult enough to own up to the mistake. An elaborate excuse doesn't need to be made. Things just may not work out the way you thought and you now want to go in a different direction.
I've been fired from editorial jobs before. My vision and the vision of the creator weren't matching, so I was let go. It happens, and I've got no animosity toward those creators or their projects. It's about trust. It's about doing the best thing for your project, and being an adult while you do it.
Being truthful with creators will get you noticed and keep you in good standing in their eyes. Anything else can hurt your reputation...and if you're just building it, damaging it now could be very challenging to overcome.
Something to think about here at the end of the year.