Hello. If you can log in to your computer you can go to the control panel to change the password. If not you'd better to refer to a third-party tool to change it. You can firstly reset the password following the steps below:
Step 1: Download and install Windows Password Recovery Tool on any available computer.
Step 2: Insert a bootable CD/DVD or a USB flash drive on the computer. In the pop-up window, select “Reset Windows local account password”, choose your CD/DVD or USB flash drive, and click “Burn”.
Step 3: Start you PC and insert the newly created CD/DVD or USB flash dive on the PC.
Step 4: After the program initializing, choose the Windows installation, select administrator account, enter a password, click “Reset” and “OK” in the pop-up windows and click “Reboot”.
After resetting the password then you can set a new password to login.