You have removed the guest user which is required in punbb.
<id>1</id>
<group_id>2</group_id>
<username>Guest</username>
<password>Guest</password>
<email>Guest</email>
<email_setting>1</email_setting>
<save_pass>1</save_pass>
<notify_with_post>0</notify_with_post>
<auto_notify>0</auto_notify>
<show_smilies>1</show_smilies>
<show_img>1</show_img>
<show_img_sig>1</show_img_sig>
<show_avatars>1</show_avatars>
<show_sig>1</show_sig>
<access_keys>0</access_keys>
<timezone>0</timezone>
<dst>0</dst>
<time_format>0</time_format>
<date_format>0</date_format>
<language>English</language>
<style>Oxygen</style>
<num_posts>0</num_posts>
<registered>0</registered>
<registration_ip>0.0.0.0</registration_ip>
<last_visit>0</last_visit>
That is what the guest user has so you have to re create it with them settings. I dont have a better way of giving it to you.
This is the best tool to removing uses without doning something you shoudnt.
User Management. Created by Connorhd. The User Management plugin can be used to prune user accounts based on the age of the account and the number of posts made by the users. Additionally, the plugin can also be used to add new users. Updated 2005-03-01.
Also you should make backups of your database before doing things like this.
Sorry. Unactive due to personal life.