ALTER USER postgres PASSWORD null; now has locked me out of psql

I have installed postgresql version 9.3.14 on High Sierra via HomeBrew. Upon trying to access the server via psql, I was being prompted for a password for the user postgres. Using postgres as the password got me into the database, but I was confused, as I have never been prompted for a password for the default user before. I looked around online on how to circumvent this, and I tried the solution suggested by lalligood on https://dba.stackexchange.com/questions/83164/remove-password-requirement-for-user-postgres?newreg=aa34aebf18274762924df4fb035dedff which was to run alter user postgres password null; and now I cannot access psql. Trying postgres, null or omitting a password does not get me in, and I do not know what to do.