how to remove from the span control generated

When I create this form entry
<p>FirstName* [text* Firstname 50/50]</p>

HTML produce this code:
<p>LastName* <span class=”wpcf7-form-control-wrap Lastname”>
<input type=”text” name=”Lastname” value=”” class=”wpcf7-text wpcf7-validates-as-required” size=”50″ maxlength=”50″></span></p>

how can I remove the
created in the span????

thanks for your help