If a person is hired and does not want to work at the place any longer within the 90 days, what are the steps that need to be taken to leave the job?
Is there a 2 week notice or anything required?
What if the employer wants to get rid of the person within the 90 days, what are the laws concerning that?

I really never get a clear cut answer on this so I wonder what the answer really is.

Thanks

The answer is that within or outside 90 days makes no difference whatsoever.

If you want to quit, you quit. Unless there is a binding contract that specifically says otherwise, no notice is needed. It is a courtesy, but it is not required by law. It doesn't matter if you're still within 90 days or beyond it; for purposes of this discussion, the only state where the probationary or introductory period has any legal status is Montana. It MIGHT, in some states, matter for purposes of unemployment (though it will make a lot more difference WHY you quit) but it has nothing to do with the legality of quitting.

The same goes if the employer decides they don't want you working there any more. It doesn't matter whether you're still within 90 days or not; all they have to do is tell you that your services are no longer required. The sole caveat is that you cannot be fired for a reason specifically prohibited by law, but that is also true regardless of which side of day 90 you are on.