Hi,
Please check the below note. Please check the PDF attached in the below node.
Note 73606 - Supported Languages and Code Pages
Unicode System
Every new installation of an SAP system is Unicode.You can only deselect this option if you perform the system copy for a non-Unicode SAP system that has been upgraded to the current release.If you install an additional application server instance in an existing non-Unicode system (that has been upgraded to the current release), the additional application server instance is installed automatically as a non-Unicode instance. The installer determines if a non-Unicode system exists and chooses the right executables for the system type.
Every new installation of an SAP system is Unicode. You can only use the non-Unicode kernel if you perform the system copy for a non-Unicode SAP system that has been upgraded to the current release.
All the above lines have been picked from Installation guide.
Thanks
Rishi Abrol