Run this command from bash:
ALLOW_PASSWORD_CHANGE=1 /scripts/realchpass User Password
Here,
User
is the username you wish to change for.Password
is the new password.
So, replace them with credentials of your choice, such as root and 12345.
Example
ALLOW_PASSWORD_CHANGE=1 /scripts/realchpass root 12345
This will change your cPanel's root account password to 12345.
Note:
Please do not actually use 12345 as it's insecure
and extremely easy to crack.
So choose the passwords which are much more secure
.