Changing windows password without knowing old

Step 1 :

Start Menu > Computer > Right Click > Manage

Step 2 :

System Tool > Local User and Group

Step 3 :

Double Click on User  (exp. your  Pc Name )

Step 4 :

 Chose User > Right Click on It > Set Password

Step 5 :

Click on Proceed button

Step 6 :

Then Set your New Password