Deleting incremental files

There is no option provided to do what you ask.

The only option would be to use the Clean up versions tool to try to remove unwanted incremental backups but you may find that this is not possible after a new full backup has been created.

Ok. But what if I copy the fullbackups away (explorer) with no incrementals. I can add this files (arrow left below) if needed and access the content?
If I add more then one, do I have to search each separately or can I choose a date (kind of merge them together)?

Thanks. 

If you copy files belong to existing backup tasks to other places then they are most likely to be reported as being corrupt because of the associated metadata and database information.

You would be better advised to setup another backup task using only full backups to a second backup location which would achieve the same end result while able to be automated if you set the right cleanup rules for both tasks.

I acutally wanted to avoid to run 2 backups but with what you say, I will do it that way.  

Thanks a lot.