I recently installed Mandrake 9.1 on a windows 98 system. I created 2 partitions to do a dual boot. Now i formated the linux partition to rid of linux. Now the LILO boot manager is still on my computer, i think its still in my C: drive with windows 98 or somewhere else. How do i get rid of it?

Boot with a Win98 floppy disk with fdisk.
execute command:

fdisk /mbr

This wont erase my 98 files would it?

Nope. Just repairs the MBR.