If you’re looking for iMovie Theater in iMovie on iPhone
Sharing to iMovie Theater is no longer supported. If you’ve shared movies or trailers to the Theater in previous iMovie versions, you can still view, share, and delete them. To continue to view movies or trailers you’ve shared to the Theater on all your devices, import the movies or trailers into Photos and make sure iCloud Photos is turned on. After you’ve imported all your movies and trailers into Photos, you should delete them from iMovie Theater.
Add movies or trailers in iMovie Theater to Photos
In the iMovie app
on your iPhone, tap the More button 
in the lower left of the Projects browser.Tap View iMovie Theater.
Tap a movie or trailer to see more details.
Movies or trailers that have been uploaded to iMovie Theater but are not stored on your device appear with a cloud icon
. Tap the Download button 
to download the movie or trailer to your device.Tap the Share button
, then tap Save Video.To view your movie or trailer on all your devices, make sure iCloud Photos is turned on (go to Settings > [account name] > Photos, then turn on iCloud Photos). See Set up and use iCloud Photos.
Delete a movie or trailer from iMovie Theater
When you delete a movie or trailer in the Theater, you can choose whether to remove the movie or trailer only from iCloud or from iCloud and all of your devices. Your source project and related media aren’t deleted, which means you can edit the project again.
In the Theater, tap the movie or trailer you want to delete.
In the details screen, tap the Delete button
, then tap one of the following options:Remove from device: The movie or trailer is still available from iCloud but is removed from the device.
Remove from iCloud: The movie or trailer is still available on the device but is removed from iCloud.
Delete Everywhere: The movie or trailer is removed from iCloud and all of your devices.