Hi Anne,
You can not delete directly master data if it is used in other data targets.
You need to make sure this master data is not being used anywhere. First you need to clear all dependencies (i.e., wherever this master data is being used in data targets) then only you can delete this masterdata.
you can serch on this you will get lot of information.
why we can not delete?method of deletion etc.
hope you resolv your issue.
Regards,
Ganesh Bothe