Hi,
I have PC running already with Zorin OS using 1 SSD.
I have another external SSD which earlier was using on this same system which is running Windows 10.
I'm fine with switching between boot order in order to enter any specific OS.
Can I now connect that other SSD with Windows 10 along with Zorin OS SSD ?
what other steps I need to take ? since I disabled few things in BIOS for Zorin os.
Gday @Steel
Yes you can plug-in the external drive & leave it plugged in if you wish.
To save you using the BIOS to change boot order, you could install a grub (boot loader) to save opening the BIOS, but it is almost the same time to change BIOS as it is having a grub interface.
Hope this helps.
I can confirm all works fine. I needed windows cause there are still some games which run only on windows. And Zorin os for work purpose is great.
Yes i run some windows programs too, but i use "Boxes" a virtual machine & load windows there 
But you may have all your information on the other drive & it makes it easy for you to run it like this.
Another way to setup your system.
Is to permanently set the priority (1st boot order) boot in BIOS to "USB",
then 2nd option set to Internal SSD.
Save
What will happen if you have the external drive plugged-in it will boot from the external drive,
if you don't have the external drive plugged-in then it will choose the next bootable drive, "Internal drive".
So it's sort of automatic