Remove file from backup when it has been deleted from source

Hello, I have read a lot about this subject, but it’s still not clear to me.
For example: my backup set (source) is:

1.jpg
2.jpg
3.jpg
4.jpg
5.jpg

I have backupped them.
After a while I remove 3.jpg from the source. I want it to be deleted from the backup (server side) also. How can I do that with the GUI or a command?
I also use another backup solution. There is an option “Archive cleanup” that does the job. I really hope there is such an option for Duplicati too.

Thank you in advance!

Welcome to the forum @Doedoedoe77

Saying what’s not clear would help, otherwise people might just repeat.

It should instantly vanish from the Restore list of the backup. Because you may have it in old versions which you can see on that Restore dropdown, the file cannot be deleted until no version includes it, or you force deletion anyway, for example with the purge command. Duplicati does not do direct file copy onto the destination, so deleting a given source file will not instantly release its space which is shared.

Overview
The backup process explained
Compacting files at the backend
The COMPACT command
How the backup process works

You’d have to say what that does, but Duplicati cleans up unless you set –no-auto-compact=true.

Thank you very much, you are totally right.