Please know that permanently disabling the pop-ups that ask you to link accounts or other tips is currently unavailable. However, I've got steps to ensure you can perform alternative ways to achieve your goal.
Pop-ups or Ads help you explore things you can do more with QuickBooks Online (QBO). Since you need to disable this, I recommend disregarding them by clicking the X or No, thanks option.
Moreover, you can also install a pop-up blocker in your browser. You can follow the steps below depending on the browser you're using.
Google Chrome
On the left of the address bar, click on the lock icon.
Choose Permission for this site (Mozilla browser) or Site settings (Google Chrome).
Proceed to the Pop-ups and redirects section.
From the drop-down menu, select Block.
Safari Browser
Open your Safari browser.
Pick Safari, then Preferences.
At the top, select Websites.
On the left sidebar, pick the Pop-up windows.
Choose Block in the pop-up menu for the website.
In case you need to see different guidelines on how to effectively handle your business using QBO, you can read this article: Help guides for QuickBooks Online.
You can inform us anytime if you have other specific tasks you'd like to complete inside QuickBooks or need further assistance managing pop-ups within the program. I'll be here to help you out again, kmwood-sugarbush.