No you will have to re-enter the bill after deleting the expense.  You can give feedback about this feature in the Feedback tab by clicking gear icon, then click Feedback.  Write your idea in the box and submit, it goes straight the the developers and engineers of the QuickBooks Online Software.  Now, if you don't want to pay the bill through QuickBooks, you can leave the expense, once the transaction comes through the bank feed for review then you can add/match that transaction to the expense and that will offset it as taken care of.  I hope that makes sense and if you want to pay bills in your product then it has to be entered as a bill for that feature.