Remove unused imports

common/djangoapps/course_modes/admin.py

@@ -4,7 +4,6 @@ from django.conf import settings
 from django.contrib import admin
 from django.http.request import QueryDict
 from django.utils.translation import ugettext_lazy as _
-from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
 from pytz import UTC, timezone
 
@@ -22,7 +21,6 @@ from course_modes.models import CourseMode, CourseModeExpirationConfig
 from lms.djangoapps.verify_student import models as verification_models
 from openedx.core.lib.courses import clean_course_id
 from util.date_utils import get_time_display
-from xmodule.modulestore.django import modulestore
 
 COURSE_MODE_SLUG_CHOICES = [(key, enrollment_mode['display_name']) for key, enrollment_mode in six.iteritems(settings.COURSE_ENROLLMENT_MODES)]