You created a custom OWL with a Delete button, but it appears as if disabled and doesn't work only in the RUI / Fiori interface.
SAP Cloud For Customer
Direct delete action for non-SADL OWL is not supported.
For this to work properly you should create a SADL OWL instead.
Delete Button; SADL; RUI; Disabled; Custom OWL; , KBA , AP-RC-UIF-RT , UI Framework Runtime , Problem