Delete Your Sample Accounts

Unless you want to keep your sample accounts so that you can play with them in the future, run this code to delete them.

Enter this code in the Force.com IDE’s Execute Anonymous pane, in the Source to execute field.

1List<Account> buggyAccounts = [SELECT Id
2                          FROM Account 
3                          WHERE BillingCity = 'Suffragette City'];
4delete buggyAccounts;

Click Execute Anonymous.
In the Accounts tab of the Salesforce user interface, verify that your accounts have been deleted.

Force.com IDE Developer Guide

Delete Your Sample Accounts