Only system administrators with the permission to impersonate users can perform these steps.
1
Click here.
2
Click Setup.
3
Click the "Quick Find" field.
4
Type "users"
5
Click "Users"
6
Find the user you want to impersonate. Click "Login"
7
You will see a warning at the top that you are logged in as another user. You can perform most functions as the user. When you are done you should log out as that user.