remove locked field from header

hey all,

i`ve got a field (default locked by system) twice on a form. one is in the body of the form the other one is in the header.

i need to remove/replace the one from the header, but this seems to be impossible.  there is also no way to move it in a hidden section or something, because this field is in the header.

how can i solve this issue?

thanks in advance

markus