When using a control file to remove an Ftmap attachment by its khubId, add the following lines to the FluidTopicsControlFile.xml file:
<?xml version='1.0' encoding='utf-8'?>
<controlFile>
<resources>
<resource>
<originId>$FTMAP_ID</originId>
<attachments>
<attachment>
<isAttached>false</isAttached>
<khubId>$ATTACHMENT_KHUB_ID</khubId>
</attachment>
</attachments>
</resource>
</resources>
</controlFile>
Be careful not to confuse the originId metadata associated with a map attachment and the originId metadata associated with a map. The first is defined at the attachment level within the node of an Ftmap file. The second can be retrieved in the document's Metadata journal.