Take leading ZERO out of a phone number

Hi, we are using an EMAIL to SMS message engine to send out SMS via Knack, but the engine requires the stored mobile number to be submitted without its leading zero. I can figure out how to replace the zero with a space and then pull it out, but it also replaces any other zero as well ... can anyone think of an easy way to strip off the leading zero please?

thanks

Andrew Steele (UK)