can you delete this?

The update installer program or zip file that you downloaded for each update might well not get deleted each time you get & install the next update, but they aren't very big.

Java does not delete old versions of its programs automatically.

If you have windows XP right click on <start> select explore, scroll down to and select <program>, find and open a folder called <Java> Highlite and delete all old Java folders. the most recent java file is 1.6_01. Delete all folders to your recycle bin that way you can test your system for a week or so and restore if problems occur (which shouldn't happen but best to be safe).