I can easily add the extension for a user with the user email and the extension data in the request body, for example:
"<user><extension_attributes><extension_attribute><id>1</id><value>1</value></extension_attribute></extension_attributes></user>"
To remove the extension I have tried to do a PUT with https://ocean.jamfcloud.com/JSSResource/users/email/${email} and with the request body as the xml from the results of the GET User API without including the extension attributes.
Appreciate any suggestions,
Janet