Hi there, @grahamskinner77.
The QuickBooks Online Sole Trader app does not have the feature to make customers inactive.
To do this, we can open a web browser, go to the customer's profile, and set their status to inactive.
Here's how you can do it:
- Sign in to your account.
- Go to the Customers and Goals section, then click Customers.
- Choose the customer you want to make inactive.
- In the arrow drop-down, select Make inactive button.
- When the message "Are you sure you want to make your *your customer's name* inactive?" appears, click Yes, make inactive.

Please respond to this post if you have additional concerns related to QuickBooks.