Make sure there isn’t just one administrator account on the computer that you wish to remove. If the only admin is removed, you can’t remove a user account that is the sole administrator; however, you may either turn one of the other accounts into an administrator or start a new administration and then delete the old one.
Open the Mail program on your Mac and go to Preferences > Accounts. Select a user, then hit the Remove button. Note: If other applications on your Mac make use of this account, you’ll be prompted to delete it from Internet Accounts System Preferences.
On the bottom left, look for Users & Groups. Select the padlock symbol. … Enter your password. Select admin from the left-hand menu and then choose the – sign at the bottom of the screen. From the list, select an option and then Delete User to remove it from your account.
Please make sure you are logged in to a user account with admin privileges. nClick Users in System Preferences. select the account you’d want to delete and press the – sign under Login Options. choose whether you’d want to preserve or erase the home folder.
You might try highlighting the Mailbox in question by going to Tools, then clicking on “Mailbox” and selecting “Rebuild.” Then try deleting the mailbox by right-clicking or ctrl-clicking on it and choosing Delete from the menu.
