Looking at your initial question, it was:
How do I word this email please?
Which is something we don't do, we aren't a "how to write" site. However we will be able to offer advice on how to communicate with someone else. In this format of your question you aren't appearing to focus on the actual interpersonal skill, and more on the "Please help me write an email to tell A X."
Thankfully, another member of the community has worded it to be more appropriate as an IPS question:
How can I tactfully inform our friend that they will no longer host our game without offending them?
This asks the question of how you can inform your friends that you will be doing what you are doing, without offending them. This isn't focusing on what you can and can't say, but more what sort of tone you should use, and what certain phrases would do well.
The current answer actually does give you an example email to send, however answers should really instead simply give you guidance to write your own, explaining how you should say it, and if believed to be necessary including small sentences that would be useful to have in your email.
Ultimately our end goal is to teach you the interpersonal skills necessary so you can apply them yourself to your current situation - rather than just dealing with it for you. A useful analogy may be to think of it as homework, your first question was essentially asking us to do it for you, however the current format is more focused on asking us to help teach you the things you need to know to do the homework yourself.