And what "calendar window" of what "Schedule View" in what File? How is that file designed. Not knowing how the file is designed severely limits anyone's ability to help you with it.
Best guess is that the file was copied via that drag and drop into a container field on the layout in that window. If so, you may be able to click on the container field and press the delete key to delete this copy of your PDF file.
I understand the limits to this question. That said I am an end user, not the designer. I have no permissions to view in layout mode. I have read enough to agree it was dropped into a container field, but cannot select the field it appears in - its almost as if it were underneath. Its position never changes day-to-day.
Is there a way to search for the PDF as an attachment? Or search the day it was dropped?
You'll need to consult with the designer of the file. FileMaker Pro is a database development tool There are a great many different ways that that layout and it's underlying tables and relationships could have been designed. Someone with Full access and that knows FileMaker would need to check over the file and see what happened.
Note: If this is a global field or field in a related parent record, you could easily see the same file no matter what record you are on.