I have the steps you can perform to delete the payments from a deleted bank account in QuickBooks Online (QBO), @Ennovy. 

Deleting a bank account won't remove the transactions associated with it. It's because we want to make sure your books are intact and accurate. Since you want to delete those payments, here are the outline of the tasks you'll have to perform: 

• Reactivate the bank account.
• Delete the payments one at a time.
• Inactivate the account again. 

I'd first suggest logging into your QBO account using a browser. Some features aren't available in the mobile app on your tablet, such as reactivating the bank account. Once signed in, let's go to the Chart of Accounts menu to complete this task. I'll guide you how. 

1. Go to Accounting from the left menu. 
2. Select Chart of Accounts.
3. Click the small gear icon on the right side that is above Action.
4. Check the Include inactive box under Other.
5. Find the deleted account.
6. Hit Make active.

The screenshot below shows you the steps. 

Second, let's manually open the payments one at a time to delete them. Here's how: 

1. Locate the restored account from the Chart of Accounts page. 
2. In the Action column, select Run report.
3. The Accounts QuickReport opens. Set the Report period to All Dates and click Run report.
4. Select the transaction to open it.
5. Click Delete from the More button. 
6. Hit Yes to confirm the deletion.
7. Repeat the process for the other payments. 

Third, make the account inactive again. To learn more about the process above, see the Completely remove deleted accounts from reports section through this article: Remove Deleted Accounts From Reports. 

Also, I want to make sure I've got you covered. Based on your "realising" term, it seems you're using the UK version. If yes, kindly refer to the steps related to the process above through this article: Remove Deleted Accounts From Reports. Just go to the same section as the US article. 

The mobile app features may vary on the tablet model you have. Because of this, I'd suggest using this chart through this article: Compare Mobile App Features. Just go to the iPad or Android Tablet column to learn more about the other features available in this app. You can also go to the Banking section to help you efficiently manage your bank transactions. 

I'm just a post way if you need further assistance. Keep safe always, @Ennovy.