How i can delete all that PlayerPrefs key on my windows registery ?
Your questions are very hard to understand; you need to provide more detail.
What is a ‘prefab key’? So you mean player prefs?
Yes
There is an option under the Edit menu in the editor to delete them all too.
Thanks that delete all from all projects or only the current project ?
The current project.
Ok so I assume I have to do it manually for other lost project
On Windows you can open the registry (search for “registry” in the search box and click on the icon that looks like a cube made up of smaller cubes coming apart), navigate to one of the following addresses, and delete the ones you don’t want under the company name. If you’re not using a company name it’ll be under “DefaultCompany”.
Editor Prefs:
HKEY_CURRENT_USER\SOFTWARE\Unity\UnityEditor\
Build Prefs:
HKEY_CURRENT_USER\SOFTWARE\
If you want you can backup the current keys by clicking on the folder they belong to and clicking File->Export. Later if you want to restore them you can do File->Import.
Thanks