You just follow the exact same steps you used to install 13. You simply need to make sure you point it to the right partitions. Boot into your installed Linux system and run
lsblk. That will print a list of your partitions and where they are mounted (if they are). For example, on my system, I get:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 465.8G 0 disk
├─sda1 8:1 0 29.3G 0 part /
├─sda2 8:2 0 428.4G 0 part /home
└─sda3 8:3 0 8G 0 part [SWAP]
That means that my root (
/) is on
/dev/sda1, my home on
sda3 is my SWAP. You will have something similar only you will also see one or two partitions that correspond to your Windows system. Take a note of which is your
/ partition and then, when prompted by the Mint installer, tell it to format that partition and install the new system over it.
Note that I have set up my
/home in a separate partition so that I can reinstall without needing to format my
$HOME. If you have not done so, make sure to make a backup of your data before installing so you'll be able to copy it back again.
Basically, the installer will probably just work out of the box. All you need to know is which partition is which so as not to overwrite the wrong one.