A possibility only; it's at least something to look at maybe.
I'm assuming that perhaps you utilized "System Center Updates Publisher" to originally publish those updates into CM as metadata only?
Run SCUP as Admin.
Option 1:
If this scup instance is referencing the original scup database, you might be lucky that you'll see all the lenovo updates you had previously sync'd. You should be able to expire there within SCUP there, and sync.
Option 2 (if none of the lenovo things are listed in scup):
Go to the pull-down upper left, Options, Advanced.
click on "Start" within the Software Update Cleanup Wizard box there.
If you are super lucky... the updates you want to expire will be listed there; and you can follow the directions to expire them there.