One register on admin

from django.contrib import admin
from .models import Section, Package, Instruction, ActivePackages


class Restricted(admin.ModelAdmin):
    actions = None
    mymodel = None

    def has_add_permission(self, request):
        assert self.mymodel is not None, "No set mymodel var"
           
        if self.mymodel.objects.count() >= 1:
            return False
        else:
            return True

    def has_delete_permission(self, request, obj =None):
        return False


class SeccionAdmin(Restricted):
    mymodel = Section

class ActivePackagesAdmin(Restricted):
    mymodel = ActivePackages

admin.site.register(Section, SeccionAdmin)
admin.site.register(ActivePackages, ActivePackagesAdmin)