Disable a default signature
1. On the Tools menu, click Accounts.
2. Click the account that you want to disable a default signature for, and then click Edit.
3. Do one of the following:
• For IMAP, Hotmail, or POP accounts, click the Options tab.
• For Exchange accounts, click the Mail tag. Under Message Options, on the Default signature pop-up menu, do one of the following:
• To disable a specific signature each time you send a message from the account, click the option "None."