2 Kicad versions

I still using the 5.1 version and i want upgrade to 8 (Windows 11)
Can i install the 8 version without delete the old version?

the short answer is: yes.

Make new user directories for your new version projects and any user libraries. Copy the old projects into them and open them there with V8. Then you can still open the originals using V5.1 if you have to.
You are likely to have to add paths to these user libraries