You are able to convert an existing Lead to a Contact within the system. This functionality will keep the person both as a Lead and a Contact. You can take an additional steps, proceed to delete them from the Leads list and the information will populate under Leads > Contacts.

Path: Leads > My Leads/All Leads

• Check the box in front of the lead(s) name to choose the lead. 
• Choose Add to Contacts from the Bulk Update Leads drop down. 

At this point, the lead is not visible under Leads > Contacts. However, there should be a black checkmark next to the lead's name to indicate that he/she is both a lead and a contact in the system.

Proceed to delete the lead in order for the lead's information to appear under Contacts. 

Once done, the new contact should be available under Leads > Contacts.