When your going to delete any object, first need to delete the connections like data source to target connected by transformations.
Like this was you have need to delete.
First delete transformations
existing delta init at info info pack
next delete info pack
later you can delete data source in bw and later at ecc side.
As of now you can delete bw side zdata source in bw side and later you can delete at RSA7 and RSA6.
Any way your at sand box, leave about that issue at RSA7.
Other wise leave about zdata source, create another data source with required name and go further to implement required data flow.