format phone number, remove "+1"

Hey Marketo community,

We have an integration setup between Marketo and Facebook Lead Ads so that when someone submits through a Facebook Lead ad form, a Marketo Lead record is either created or updated. These Facebook Ad forms include a phone number field. Those who submit through these forms don't include "+1" before the phone number field value, but these records are created/updated in Marketo with +1 proceeding the phone number value, causing issues for us in SFDC.  Is there a way to reformat these field values and remove "+1" from each record's phone number?

Daniel