You can delete an account if all these statements are true:
Under Settings, click on Chart of Accounts, then Edit next to the account you want to delete:
Click Delete. If the first condition listed above has not been satisfied, a notice appears and transactions posted to the account are listed:
If no Delete button is available, either the second or third condition has not been satisfied. In other words, Manager will not let you delete an account needed for proper functioning of the tabs you have enabled or necessary for proper maintenance of your account records.