You guys should keep in mind that something triggered that restriction. It's protecting your site from what seems an attack.
I recently had a customer ask me about this via email and, after some exchange, we found that someone had been trying to hack his account, and that's why the account had been locked for a bit.
If you're getting that restriction triggered, I suggest that you find out why and take the necessary measures, instead of just removing the protection preventing a possible attacker from breaking in.
Having said all that, you can edit the restriction so it's less strict. Just raise the number of attempts allowed before considering it an attack. WP Admin > s2Member > Restriction Options > Brute Force
You could also have a second admin account, for those times when your main one is locked, so you can go in there and reset the restriction.
But the restriction only lasts for 30 mins anyway, so it's not that bad having to wait for it to go back to normal when it gets triggered.
I hope that helps.