OK, so you're in FDISK and you want to delete all the partitions and create some new ones.
Problem: when you select "Delete primary DOS partition", it says it "can't delete a primary DOS partition while an extended DOS partition exists", when you select "delete extended DOS partition" it says it "can't delete extended DOS partition while logical drives exist", and when you select "Delete logical drive" it says "no logical drives exist"! Furthermore, if you select "create logical DOS drive in the extended DOS partition", it says "All available space in the extended DOS partition is assigned to logical drives".
Suspected cause: a bug in FDISK
How to fix? Norton Utilities' Disk Editor to the rescue (again).
Warning: this procedure will almost certainly cause you to lose all the data on the partition(s) you change. Use with caution.
You may now use FDISK to create partitions as you like.
Note: you may need to rebuild your Master Boot Record (MBR) in order to boot from a drive recovered in this way, particularly if it once hosted a non-DOS operating system such as Linux. To do this, use the FDISK /MBR command.
The procedure to follow to rebuild a zeroed out or corrupted partition table is here.