deleting smartobject background

[נווה0101]

I am trying to delet a smart object background in photoshop 2020.

I just cant delet it and save it so it will update in the original file...

file added for example

[MarekMularczyk]

You can't delete anything in a Smart Object. Smart Objects are supposed to be non-destructive.

What you can do, if you want to remove something from a Smart Object, is to mask it by making a selection of the part you want to remove and add a mask using Layer > Mask > Hide Selection

[JJMack]

You can mask the Smart Object Layer to hide the layers image content's background.  You can not change a smarts object hardened  pixels content with Photoshop Tools.  You can replace the Object  or open the objects to replace  an object's content with an image that has its background removed.