This is not a scripting issue or even a lock file issue.
I have an Excel file with one sheet.
I drag that one sheet into the ToC of ArcMap.
I look at the table.
I remove the sheet from the project.
Now the Excel sheet is locked for editing.
I return to ArcMap and close the project by starting a new one.
I disconnect the folder.
The Excel file is STILL locked. I have to close ArcMap completely in order to edit the Excel file.
This results in having to go through the full 2 minute start up (yes, 2 minutes on a 2 month old machine).
Is there any other way of forcing ArcMap (10.8) to release its grip on a file it is no longer using?