The form to change a registered agent in North Carolina is found at:

http://www.secretary.state.nc.us/Imaging/ViewIVDoc.aspx?SaveAs=True&IVaultId=9334009&IVSite=Corp&Extension=pdf&DocTitle=Document:Statement%20of%20Change%20of%20Registered%20Office%20and/or%20Registered%20Agent

and the form to make an initial designation is found at:

http://www.secretary.state.nc.us/Imaging/ViewIVDoc.aspx?SaveAs=True&IVaultId=9333948&IVSite=Corp&Extension=pdf&DocTitle=Document:Designation%20of%20Registered%20Office%20Address%20and/or%20Registered%20Agent