Is this a security flaw for Other, Others, Others... accounts having 0 (root) UID?
Each user on OS X should have a unique identifier.

Given that your Mac is not managed and that you do not want the three Other accounts, reassign these accounts to different UID values – or delete them.

See Accidentally created user with duplicate UID. How to fix? for steps on how to reassign or remove these errant accounts.

This dscl command should work and form the basis for removing the other two accounts:

dscl . -delete /Users/Other


Be careful and please take a back-up first!