Give them a call and tell them that you can't provide you service for them anymore.Explain why and if they still really want your business,tell them it will cost more $$$$$.To me the best way to get rid of a client is to give them a large price raise.If they quit,too bad.If they contine then you have a nice raise!!!!That's how I do it!
If you don't want to account. I agree with bill send out a short letter 2 to 3 sentences.
Thank them for their business in the past.
Then state that you will no long be able to remove their snow for them.
Don't explain why you don't want them. If you do they will try to get you to service them again. It is a lot easier for them to call and say we really want you to do our snow again, then to call another contractor. If the reason you drop them is because you need more money, you will be stuck trying to come to a new price that works for both them and you.
If you don't want them anymore, don't leave a chance for you to get stuck doing them again.
Been there this season. First problem was with my best friend, total mess, I got around $ 11,000 worth the accounts for him(from his referals), he also plows, asked how he wanted to get paid. I assumed he was going to subcontract them from me., planed on giving him extra for referals, he wanted half total business. Ended up sending out a letter stating _____contractor will be assuming resposiblity & liability for your contract, kept 10%, for sales commision.
Now my only full time summer employee, second year plowing,said collesting unemployment to much hassle, will probably quit plowing and find fulltime job. Now I might have to drop to parking lots, due to lack of help, I'm trying to find subs first. Not a lot of money on lots, have to be done between 8-11am.