Hi Leung2019,
When we insert an Excel workbook in File viewer web part, it will show the bar at the bottom, this is intended behavior and cannot be customized. This is same for Word or PowerPoint file. The screenshot in this article shows the similar look.
Further, though we cannot remove the bottom bar, but if your requirement is to remove the Download icon, then there is an alternative way,
If you like and only if it fits your requirement, you can try using Embed web part, when we create an Embed code for specific workbook, we can decide not to add Download file icon.
Here’s a screenshot showing the difference when the file in added in File viewer web part and Embed web part.
To create embed code for Excel workbook, open Excel workbook in Excel online, click File>Share>Embed, under Appearance uncheck Include a Download link.
We appreciate your understanding. Have a nice day and stay safe.
Regards,
Neha