set field to blank

hi
i can’t speak english well but i will trying to explain

im usin API Php Class and im trying to build ppp configuration menu

when im trying to edit ppp profile im using

   $API->write('/ppp/profile/set', false);
   $API->write("=.id=$id",false);
   $API->write("=local-address=1.1.1.1",true);

it work fin

but ican’t empty the local-address field

i used

   $API->write('/ppp/profile/set', false);
   $API->write("=.id=$id",false);
   $API->write("=local-address=",true);



   $API->write('/ppp/profile/set', false);
   $API->write("=.id=$id",false);
   $API->write("=local-address=none",true);



   $API->write('/ppp/profile/set', false);
   $API->write("=.id=$id",false);
   $API->write("=local-address=blank",true);



   $API->write('/ppp/profile/set', false);
   $API->write("=.id=$id",false);
   $API->write("=local-address=disabled",true);

but nothing work

so how i can do that ??

can u use ‘unset’ ?

it works, thank you

this is the code using unset

   $API->write('/ppp/profile/unset', false);
   $API->write("=.id=*F",false);
   $API->write("=value-name=local-address",true);

may help any one