When I installed Wordpress, I reflexively made my username the same as it is everywhere. Its ease of being guessed makes it that much easier for an interloper to get into my system.

The Wordpress UI says you can’t change your username. Actually you can just pop into the database and make the change.

The table is wp_users by default. You may have set the prefix to be different, but out of the box it’s “wp_”. To alter the row in question:

update wp_users set user_login="[new username]" where user_login="[existing username]";