One of the things I try to look out for in my writing is unnecessary characters. Sure, as writers, we must populate the story but when is it too much? How can we identify these unnecessary characters?
I like to use the sexy lamp test. This test doesn’t apply only to the relevance of a female character, it applies to other characters as well. If you can replace a character with someone else – or a lamp in this case – they aren’t necessary. The test can also be applied to your main characters.
If, for some reason, you really want a certain character in the story because they bring something unique then, maybe the character needs more work. Flesh them out. Every character has some sort of motivation that gets them through the day and if after all that, the character still doesn’t work then, cut them. You can always recycle them for later.
Dabbling in the Art of Writing 