Depending on whether you are using Lilo or Loadlin the method differs slightly. Lilo users have to first restore their original MBR either by typing /sbin/lilo -u within Linux or typing fdisk /MBR in DOS. The next steps are common for both Loadlin and Lilo users. These are not really neccessary but just to be on the safe side I do them all the same.
Boot using the Linux installation CD and type Linux expert at the first prompt, answer whatever you wish to the next questions until you get to the install selection screen. Here select Install and With Fdisk and use Fdisk to delete all Linux partitions. Write the changes to disk and Ctrl–Alt–Delete your way out of the installation program or reset your system to reboot. Remember to change the BIOS settings to boot from the hard disk or else you will reboot from the CDROM again.
Reboot once again, this time with the fips disk that has the backup of your partition table and boot sector – you saved it, didn't you? – and type restorrb at the prompt. Answer yes to the question, the program will restore your partition table and boot sector and you can pat yourself on the back for accomplishing the impossible – reclaiming lost partition space! This is all the more reason for making sure that the crucial backup file (Rootboot.000) is saved in at least 5 different locations. You can never be too careful. Reboot back into Windows and run scandisk on the newly increased C drive. It will report one error in the fsinfo sector which is just a used and free space accounting error. Your Linux data is now naturally lost for ever. Hopefully this procedure won't be neccessary unless you are increasing space allocated to Linux or getting rid of Windows.