MeasureStoreException: Cannot delete non-informal position in domain

Version: 13.2.2.37

Uesr created a placeholder SKU in RPAS. SKU is toppest dimension in PROD hierarchy. SKU -> STLE -> BRCL -> ......

As the SKU was created by user and informal position in RPAS, I tried to convert it to formal and purge it from backend.

First I found it's ID and prepared dpmposupdate.xml file under <domain_path_name>/input/ path

$ printArray -array /rpas/prd/na/domains/liallb/LIA/data/hmaint.dim_sku -allpopulatedcells | grep 'PR 66TS UAO5D1'(GNGF $BUF$SKU$B5315B601031D363):    "GNGFTG_GF"                (PRDN $BUF$SKU$B5315B601031D363):    "PRDN201607"               (LABEL $BUF$SKU$B53337665A3D23C1