You can delete:
-entries in grub.conf
what about the ".config" file..........as far as i know it will work as the starting point while compiling the kernel further...am i right??
Yes, that's right, just note that you can't use a 2.4 config file for a 2.6 kernel.
Also, each time I compile a new version of the kernel and I consider it succesful, I copy the .config file to a separate folder, which I call kernel_configs, naming them .config-X.Y.Z, so I can use them in the future if needed.
Also, after compiling and installing a kernel, while you are in the directory where you unpacked it, you may run 'make mrproper' to revert the source to the original state. Note that it will erase the .config too. Afterwards, you can repeat the compiling if you wish.