Hi - you will have to convert it to a CAB file - simply change the file extension from .XSN to .CAB and then you can open the CAB and copy the files out to another folder. If your files do not display extensions for known file types, I think you can make the change in the properties window for the file.
From there, you will be able to see all the files - InfoPath is saying that in the manifest.xsf there is a file reference to people and positions.xsd but that the file is not in the form. Open the manifest in a text editor. Find the people and positions.xsd file ref and remove it - the XML you need to remove will look something like:
<xsf:file name="Lead Auditors 2.xsd">
<xsf:fileProperties>
<xsf:property name="namespace" type="string" value="http://schemas.microsoft.com/office/infopath/2003/dataFormSolution"></xsf:property>
<xsf:property name="dataObject" type="string" value="Lead Auditors 2"></xsf:property>
<xsf:property name="rootElement" type="string" value="myFields"></xsf:property>
<xsf:property name="useOnDemandAlgorithm" type="string" value="yes"></xsf:property>
</xsf:fileProperties>
</xsf:file>
Depending on the file type - you may have more or less properties, but you'll want to remove the entire file node. Then save and close the manifest.xsf. Now, right click manifest.xsf and select design. Hopefully, your form will open in design mode. Then you can use Save As to pack it back up as an XSN.