How long have they been working for you?
If it is less than two years (if they started on or after 6th April 2012), then this is the best situation. You don’t need any convoluted manoeuvring to part company.
You can just say to them that it “isn’t working out” and pay them their notice. You always have to pay them their notice, unless you have something in your contract – we will come to that later. Or if they have committed gross misconduct. But in that case, you would have to follow the disciplinary process to get rid of them.
This ease of separation is because there is now no protection from unfair dismissal in the first two years of employment (and for those of you who remember, yes it did used to be only one year before they had protection).