The following query lists the boot images registered with the server including detected boot images.
select * from dbo.csm_object where class = 1006
Using the output from the first query, delete the detected boot images using the name/id using the following queries:
delete from dbo.csm_object where id=<name/id>
delete from dbo.csm_property where object=<name/id>
*** Note: Please take a backup of the the MDB before performing any delete action just in case a restore is required.