Can you convert a bill to an expense?

two different things

a bill you get from a vendor, what the bill is for might be an expense, an item, or an asset.  You determine that by what you select on the bill

Welcome to the Community, @sphillips1.

I'm happy to provide some insight into converting a bill to an expense.

At this time, it's not possible to convert bills to expenses, you'd have to delete the bill and manually create the expense. Below I've included the steps on how to delete the bill and create an expense.

Delete a bill without opening it:

1. Go to Expenses.
2. On the Expenses tab, locate the bill to delete.
3. In the Action column, select Delete from the drop-down menu.

To create an expense:

1. Click the + New button.
2. Select Expense.
3. In the Payee field, choose a vendor. You can choose the name of a person or business. 
4. Select the Payment account to which to credit this expense.
5. Enter the date of the purchase in the Payment date field and specify the Payment method for the expense.
6. Type in the amount of the purchase and any Tax paid.
7. Click Save and close or Save and new.

You can check out these articles for more details:

• Enter, edit, or delete expenses in QuickBooks Online
• How to delete a bill

Please know I'm only a post away if you have further questions. Wishing you continued success. Take care!