Hello Cowboy,
That partition you carved out for Linux, you will want to keep in unformatted and do no assign any drive letter is it will be converted to a Linux partition. You should not have to disable the UEFI boot however, you may need to disable the secure boot option in Bios to allow you to boot the Linux Mint ISO / USB.
If you click here you will find a detailed writeup with videos for dual-booting Linux Mint and Windows 10. Be sure to make a complete backup of your Windows OS before proceeding.