Linux system password forgot not to log in how to do

First, by entering Single-user mode, modify the password and log in again.
First step:
Reboot the system and press the "ESC" key in the upper-left corner of the keyboard before entering the system to enter the following page:

Then press E to enter the edit page
Step Two:
After entering the following page, through the keyboard to select the top and bottom of the kernel line, and then press E to enter the editor, at the end of the add parameter single, so that the system boot directly into Single-user mode, and then enter the Save editor, back to the previous step of the interface, click on the keyboard on the B-boot system.

Step Three:
After reboot into Single-user mode, input passwd modify password, and then restart the system, you can use the new password login system

What are you waiting for?