I m using multiple booting system viz Windows home and Linux 13 along side. However, I wud like to uninstall Linux 13 and install Linux 17, instead. Pse guide me

What I do is split the partition. /home gets it's own partition. That way you can upgrade without affecting your files. This isn't foolproof though as some apps do not gracefully transition their .files. Close enough for me.

You asked a very general question so here's a very general answwer. Install Mint 17 to the same partition or partitions on which you have Mint 13. Back up any personal data first. Using a separate /home or data partition is always a good idea.

You don't "uninstall" operating systems the way you do applications, you simply format the partition(s) and install.

I suggest you do a fresh/clean/new installation of Mint 17. The main reason for this is that there are too many differences between Mint 13 and Mint 17 due to a further ongoing development of several (system related) packages and/or libraries.

Best to do is creating a backup of all your important files and then fully wipe your harddrive with a live-cd of Gparted. Then boot up with a live-dvd of Linux Mint 17.

Having a separate /home partition won't add any extra value to your system. Anyone who is aware of the risk of a crashing hard drive or failing operating system always makes a backup of his/her important files. And these backups will be saved on an external device, most probably dual layer DVD's or USB flash drive (which itself creates an unsafe situation since USB Flash drives can stop working too).

On the contrary, it can add a great deal of value.
Simply re-install using the old /home and the same users. Works a treat.
I actually keep the old system on separate partition(s), and can fall-back with a simple re-boot. Doesn't preclude backups as well, but simplicity has its own value. Especially for new users.

Of course you are not going to wipe your hard drive. That would require re-installing Windows.

You can install Mint 17.2 to your Mint 13 partition. Formatting the partition is normally part of the installation process. No "un-installing" necessary.
You have the option of installing Mint 17.2 to a different partition (you may have to create one). Then you would have both Mint 13 and Mint 17.2 to use, which might come in handy under rare circumstances.

You should always have all important data backed up to an external location. That is just Standard Operating Procedure.

Of course do backup if you haven't already. Daily backups can be very useful. Do both Windows and Linux in case something goes wrong. I just tar and gzip everything.

Personally, I would use the live Linux Mint 17.2 CD and Gparted which is on this CD, and format the linux partitions you have. Drives sda1 and sda2 or hda1, hda2 are usually the Windows partitions. So format the rest or delete the linux partitions entirely and then while there try installing Mint using the desktop CD icon. If this doesn't work you may need to reboot and then use icon to install LM17.2

Having a separate /home partition doesn't add any value. The reason for this is:

1) If you backup your documents, you always do this on an external device as an extra measurement in case your hard drive dies or fails. A separate /home partition still is part of the very same hard drive on which the partitions are located on. And when your hard drive dies, so does all those partitions including that separate /home partition.

2) When upgrading or re-installing your Linux version, you don't want to have all those old application settings files being around. When upgrading your Linux version the old application settings files can cause malfunctioning. Even when you re-install Linux it can lead to malfunctioning due to file version conflicts, differences in package names and so on. It is easier to copy the application settings files you really need to an external device and later (after re-installing Linux or upgrading Linux) copy them back to its original location.

3) Having a separate /home partition really doesn't offer extra security.