click on "Forgot your Login?"

???
So if you can’t do that - maybe because it is a local development site with no email service - you need to edit the password in the database
So: on another install -
create a user with a simple password - say 11223344
in the modx_user table retrieve the password (after it has gone through all that hash/salt stuff) - mine was: d54d1702ad0f8326224b817c796763c9
paste this into the modx_user password in the database for the install that you are locked out of
login with new password (while you are looking at the database check on your username in case that is really what you forgot - been there!)
Note the password and the hashed value above may not work - better to create your own as explained with the same version of modx