How to revoke 'git add' before 'git commit' ?

Sometimes you need to undo your git file before you git comment command. Because you made a some misteck or wrong code and you did git add using "git add ." command then you think how to undo your code before git commit command. But you can do that using git reset command, if you need to undo all file Or you may need to undo just one then you can do using git reset command, you can see bellow command.

Example:

 // For Spesific file
git reset 
// For all files
git reset