@Jovychris_A 

Also, trying to follow your screen shots and info - my QBO shows Clients instead of customers which is OK. Then when I go to an invoice that is the parent | sub-client, I don't have linked transactions shown. I do have a payment made link on the top right under the PAID info. That link shows me the payment receipt. There are no REMOVE buttons, as shown in your screenshots. Are you wanting us to delete the payment receipt for that particular invoice?