Tizen has Linux kernel just like Android and Sailfish. So on lower level side of things, it is perfectly possible to install another OS on top of tizen or by removing tizen. You can install Android or Ubuntu on Tizen phone.
Factory default permissions prohibit you from removing the existing OS image, unless you know how to use root and cleaup. And this is where you need to use desktop tools to bypass the permission sets. Because the software you need to clean the bootloader of phone is often limited to the Linux and Mac operating system. Most of the tools to achieve this are specific to desktop tools on Linux. Instructions however will vary depending on the type of desktop operating system you have.
In case of doing all this tampering on Windows you may find that it'd be harder to format the phone bootloader and install another operating system. There are ways to bypass those issues using Virtualbox with linux on it.
If you are comfortable with tampering with hardware then this may not take much time for you to do. Here are some steps that you can do.
1. Find out how to break the root access of the device.
2. Format the device with file system of OS, you wish to install.
3. Install new bootloader.
4. Copy the Android image on device HDD.
5. Run the bootloader with android image setup.
6. Install Android OS of your choice.
Do note that if you overwrite with root access on your phone then your warranty is void from that moment. Also if your bootloader doesn't properly format then you may get into permission issues while installing android. I'd say don't waste your money and time in doing this as there is no performance benefits or any benefit for that matter to do this with Z1.