If informal and formal steps to improve performance do not work, you can dismiss your personal assistant. Because being a PA is not part of regulated professions there are no external tribunal procedures that you can pursue.
If your PA has worked for you for less than 2 years, you can dismiss them with a week’s notice. If it has been longer, you should give a verbal warning and then a written warning before terminating their contract. Your PA may find it awkward to come to work during their notice period.
If your former PA takes you to an employment tribunal (GOV.UK), seek employment law advice through a local law centre, Citizens Advice or someone with specialist HR knowledge.
If your PA has worked for you for less than 2 years, you can fire them with a week’s notice, unless their contract states otherwise. If they have worked for you for more than 2 years, the minimum notice period is 2 weeks.
The length of minimum notice period increases by a week for each year of employment, up to a maximum of 12 weeks. You should pay them as normal during this period.