How to change password

If you know your admin’s user name (or email address), then use that on the ‘lost password’ screen. Then click on the link in the email you will get to change it.

BTW, a user called ‘admin’ is not really good practice. That is halfway to getting the credentials for your site, but some ‘rainbow attacks’ that try to guess your password. I never use a user called ‘admin’, especially with an admin-level access. (Sometimes I demote that user to ‘subscriber’ just to irritate hackers to spending their time on it. But only after creating and logging in as the new admin-level user.)

If necessary, and you have phpMyAdmin access, you can go to the wp-users table and set the password there. (Or change the email account associated with that user, then use ‘lost password’.) But using the ‘lost password’ thing is faster and a bit easier.