hide site label from django admin

I am a beginner in django and i used sites framework to make multiple instances of a website use the same code and database but in my django admin page i noticed that it display a label site in each model to make the get or create queries based on the selected site but i want to make it use the current site to get or create objects and remove this selection from all models.

how can i do this ? thanks.

This is the admin.py code in my models:

from survey.models import *    
from django.forms.models import ModelForm
from django.forms.widgets import RadioSelect
from django import forms
from django.utils.safestring import mark_safe
from django.contrib import admin

admin.site.register(AnswerRange, AnswerRangeAdmin)
admin.site.register(Role,RolAdmin)
admin.site.register(Indicator, IndicatorAdmin)
admin.site.register(CharacteristicCategory)
admin.site.register(Characteristic, CharacteristicAdmin)
admin.site.register(Practice, PracticeAdmin)
admin.site.register(UserProfile, UserProfileAdmin)
admin.site.register(Macro)
admin.site.register(ReportPassword)
admin.site.register(Demographic, DemographicAdmin)
admin.site.register(Message)
admin.site.register(Comment)
admin.site.register(InstanceSetting)
admin.site.register(UsersWaitingList)
admin.site.register(ticket)
admin.site.register(Answer)
admin.site.register(Option)