Yes, you can end your presentation early. It is slightly different in Pro Webinar vs. Talks:
In a Pro webinar, to end your talk early, you just need to click the “End Presenting” button to the top right of your webinar presentation window..
After you have ended the presentation, your phone line will be cut off from the audience and from your fellow-presenters if you were presenting with anyone else.
In a TALKS webinar, to end your talk early, you just need to click the “End Presenting” button to the bottom left of your webinar presentation window.
You will be prompted to confirm you want to end your live talk.
Click the “Yes, end talk now” button and your talk will end. You will no longer be able to see or communicate with your fellow presenters or audience.