@Ryno @JNon This is likely because you have an invoice associated with the customer that you're trying to delete.
For proper bookkeeping services, I don't recommend deleting those invoices, but what you can do is Edit your invoice and change the customer associated with it. To do this,
1) Navigate to the Invoices page
2) Click on the invoice associated with the customer you're trying to delete
3) Click "Edit invoice"
4) Click "Choose a different customer"
5) Click "Save and continue"
Once you have done this for all invoices associated with the customer you're trying to delete, you should be able to go to your Customers page and delete the customer using the trash can icon to the right of the customer's name.
Hey @JNon, you should see the trash can icon to the right of your customers name, in Sales > Customers on your account. I have attached an image of what that should look like, if you are seeing something different, would you be able to attach a screenshot of what that looks like in a response? Thanks