Intuit's investors are more important than our experience on their platforms.  
Do not expect an option to disable ads.

Ever. 

However, there is a workaround I'm using.

Some time ago, in order to undo a reconciliation, Intuit support directed me to make my own accountant profile and added my own company as a client. As far as I can tell, a QBO accountant profile doesn't have ads or promotions (they don't want to bother accountants, but ordinary users are fair game $$$).