Well, if you want to remove all the seeds listed in the VST, then u have to delete the VST file.

Follow these steps to delete the file:

>> Goto My documents

>> There should be a folder called LDW, open it, then open the plant tycoon folder

>> then delete the VSTray2*

* This will delete all the seeds u have in ur game2

Now open the VST, you should have no seeds for the second slot.

& i hope u'll do it correctly!