Digital Signature Nightmare. HELP!

Hi,

I was filling in a form, and thought I'd create a digital signature instead.  I assigned it to an e-mail account.  Now I am unable to send e-mails from that account (a g-mail account) as the Apple mail progrmme keeps on asking me "Mail wants to sign using key 'privateKey' in your keychain". 

Is there a way to get rid of this digital signature so I don't have problems with sending e-mails?  I tried removing the signature in the Adobe app but wouldn't allow me to.

Any and all help appreciated so I can get my e-mail account back!