I do not have enough experience inTC administration and one of the most annoing things is to delete some "wrong" datasets.
jt files created by dispatcher I can delete (with some error pop-up window but still possible)
but i can`t do it for any CATPart ot UGMASTER
where should I dig to find solution? how to remove reference to Item Revision do be able to delete dataset
I assume you're in dba role. if not check the access rights.
Up to TC11 you have to delete the UPPART first before you're able to delete the UGMASTER and ItemRevision.
Check all hidden relations by adding a new preference for DBA group only: WhereReferencePOMPref=1