Problem:

Cannot delete Data Transfer Process (DTP) from DSO/CUBE to DSO/CUBE. Despite all the pre-conditions have been met, such as deleting data and requests in the target and source.

Error Message:

Delta DTP cannot currently be deleted (see long text)
Message no. RSBK037

Diagnosis
You want to delete a delta DTP that has been successfully used to load requests from the source into the target. If you delete the DTP, you will also delete the information on the source data that was successfully transferred. As a result the source data would be transferred again, if you create a new delta DTP that links the same source with the same target.

Procedure
You have two options:
1. Delete all the requests loaded with this DTP from the target and then delete the DTP.
2. Do not delete the DTP and continue to load deltas using this DTP.

Solution:

Go To Transaction RSBKDTP to delete DTP directly.

Source: http://forums.sdn.sap.com/thread.jspa?threadID=1568522&messageID=8581401

Additional Note:

Data Transfer Process (DTP) is related to various object such as Target, Source and Transformation. Here’s an extra table check for transformation. After deleting DTP, Cube or DSO  than the transformation should be deleted too.

RSTRAN Transformation
RSTRANFIELD Mapping of Rule Parameters – Structure Fields
RSTRANRULE Transformation Rule
RSTRANSTEPROUT Rule Type: Routine
RSTRANRULESTEP Rule Steps for a Transformation Rule
RSTRANSTEPMAP Mapping for Rule Step Within a Rule

Source:http://www.sapks.com/2010/01/dtp-tables.html