Need help fixing epub validation error

[Wraylewis]

I'm down to the very last details in preparing an epub file in Sigil.

I have two errors when I validate, both clearly related to a section of the book I removed:

OEBPS/Text/anotherday.xhtml NA This OPS document is reachable but not present in the OPF <spine>. "Reachable" means that a reference of some kind that points to this resource exists in the epub.

and

OEBPS/Text/anotherday.xhtml NA This resource is reachable but not present in the OPF <manifest>. "Reachable" means that a reference of some kind that points to this resource exists in the epub.

The NA means there is no line number to search for.

How can I find these references to a file no longer in the epub and remove them?

Thanks for any help you can give.