Partition Wizard Bootable CD will do the necessary.
Might be an idea to change the drive letter from J to something else and also set it as Inactive.
Then see if you can still boot and nothing complains that J is missing.
(just in case you are booting from J without realising.)
You can do this with Partition Wizard, but if problems you won't be able to change back. The Bootable CD allows you to do that.
When you are sure J is superfluous, Partition Wizard also allows Format or just delete it and Resize an adjacent partition to fill the space.