Polite way: 

" I am kind of busy not able to take another client".

A direct way:
"You have a unrealistic expectation. This strategy will not work."

A rude way:

"You want me to take you the homes as your Supra doorperson. You picked up the listing card and plan to strike a deal direct with listing agent." "Please get out my car and walk home.!" 

 I DID set one free once, and I didn't care where they went....they actually stayed with my office and another agent accepted their abuse....soooo abusive.... I took it for about 4 minutes.... and it was via a voice mail... I retrieved my sign, lockbox and left their key on their kitchen counter.... locked the door behind me...canceled the listing in MLS.... and DONE... let a voice mail for him that I just "cut him loose" and emailed the canceled listing.

Unlike Mark Twain, I have met those I  do not like and refer them out to people with more tolerance and patience.

 Most recent was a couple of years ago.  Seller would throw temper tantrums, make accusations... I told her it was in her best interest to use another Broker.  I picked up my toys and went home.

One of the two hardest lessons to learn... first, how not to take on the wrong business. Second, how to fire the wrong business... and yes, I have fired clients and as you said it's a wonderful sense of relief.

I have let clients "go".   Buyers and sellers.  Not necessarily easy but if it's not a good fit, it's best to move forward.    

Oh Lordy. 5 in the past 60 days.
ALL my listings have a mutual kickout clause - if it was an error to accept the client, I want out quickly.
Buyers, if they are in la-la land, they can go back burner, be canned outright or referred.
I need my life to be happy.

Yes, done that.

When it is time. 

For sure, you will find the answer

About once a year.

One time. Now I won't even take the clients like that to begin with

Absolutey!  Within the last year, I informed them that while I appreciated their intereset, another agent would best meet their needs.

I did that last year and yes, it was the best feeling in the world! The lady was a true _____ to work with and I even suggested someone for her to call (my least favorite agent in Charlotte!!).

Let the _____es unite!

It been a few years but I remember it like yesterday. It was a sweet and welcomed parting.

Been about 2 or so years ago

Yes, about a year ago. I too, felt relief after doing it. I did not and do not regret it for a second.

I do it all the time - I have colleagues that capable and less busy, and some people just aren't a good fit to work with.  I try to help everyone, but I'm not a fan of working with people who refuse to help themselves.

We have determined that sometimes the work load for a person is beyond the potential paycheck. A parting of the ways can be done tactfully by letting them know that you don't believe you are able to fulfill their expectations and wish them well with another agent. Then get a good night's sleep with that burden off your shoulders!

I have let them go but why would I inflict punsihment on people I like?

I came close once, but never pulled the trigger.

In the Mortgage business I have "fired" several people over my 47 years. For the most part,they refused to get me documents,or felt like, because they were putting 40,50 60% down, they should not go through the intense amount of paper work, that goes with a mortgage. I just said, that maybe it is best you use another mortgage banker. After I said that, almost all stayed with me. When I tell them, "I only get paid,when you close." I think they realize we are on the same team.

When I did do it...It was the right thing to do

I usually refer them to an associate.

Sure have!  And I don't feel guilty about it!  If you are truly working for the client, then it's in their best interest to have an agent that can work with them.  You can't be expected to be BFFs with everyone!

About 5 years ago I told a buyer I did not think I could help them. He was a little too picky and suspicions about everything.  I was not happy about anything!

I had a couple buyers very unreasonable with price and their needs, and did not ever say good bye, but stopped contacting them.   Never did a buyer's agency either.   KUDOS to you for letting them go, it can feel invigorating! 

It happens from time to time.

Yes! Too many agents kill themselves trying to please everyone. I work a certain way and my methods are not suitable to everyone. 

No

Christine Kankowski North SD and Temecula - oh yes. A few times - simply mentioned that we are not a good match.

It has been a couple of years and it was for a violent man, heavy drinking who would forget we spoke and yell for not talking to him, the next day would come and repeat. 

It's been a while