Delete partitions on install?
 

How can I delete partitions on install with SuSE?

what do you mean? If you mean removing the Linux partitions, restoring you system as it was before, your "rescue" disk is probably best for that, providing you haven't altered you MS partitions much. If you have, no fear, because MS explorer and so lack the ability to retrieve Linux information. You'll lose any information from this situation, but that's a fault in MS's disk reader, not Linux.

I mean removing eveything that was installed before and starting an install from scratch...

It's been a while since I used SUSE, but I think you should go for advanced setup, you will probably be able to repartition your hard disk. Simply erase all existing partitions before creating new ones.
Or if your old system is still working, you can use gdisk or fdisk to remove partitions, changes will take effect after reboot.
[red]Be sure to backup important files, you won't probably be able to go back![/red]