Hello Gunther, 

Thank you for the brilliant software and video tutorials. 

I am new to time lapse but you have made post processing very straightforward. I captured this time-lapse in aperture priority mode and have some very inconsistent exposures that caused some major flicker in the moon as you can see. I have tried endlessly deflickering that specific section of the image to no avail. Do you think this flicker can be removed? Thanks for your help! 

Password: lrtimelapse

https://vimeo.com/145175118

Best, 

Adam 

Also, how is a rectangular selection deleted?

The moon here is totally blown, I think you won't be able to remove that residual flicker on the moon fully, especially since the rest of the sequence (around the moon) is not flickering. It's not bad at all.
But next time, please shoot in M mode and use Holy Grail technique if you need to adjust for the brightness. Check out my EBook!

You can remove the reference area by double clicking into the preview.

Thank you .