You can give your own association name while creating a user and device association.
OOTB code doesn't do it currently but you can extend that code. When you call "PostEvaluate" method set the Association name in it based on either user choice or something generated by your business logic to identify the device uniquely.
Now once the Association name is correctly set in the system, you can use "ListAssociations" & "DeleteAssociation" method against a specific Association name.
Currently, this is the only way that product API supports for your business requirements.
Let say you have to have a way to get additional information, then you need write direct SQL query against CA AA database.
Refer following tables:
ARRFDEVICEINFO
ARRFDEVUSERASSO