I'm thinking of ghosting a girl from work because another friend from work is interested in me.
What kind of interest are you talking about?
She really likes me.
Finding a new romance at work does not justify ghosting another friend because of it. Ghosting people is inappropriate and inconsiderate. Not explaining why you are breaking off communications could really hurt people.
It's not like I'm her only friend, and we don't talk that much anyway.
Even so, ghosting her would be rude. If you don't want to talk to her anymore that's your decision, but at least have the decency to explain the situation to her.