Solution : https://service.sap.com/sap/support/notes/623550 (SAP Service marketplace login required)
Key words : 
call method <tree_instance>->item_set_t_image        exporting          node_key = 'root'          item_name = 'column2'          t_image   = 'bnone ', call method <tree_instance>->item_set_t_image        exporting          node_key = 'root'          item_name = 'column2'          t_image   = ' ', terms item_set_t_image, symptom superseding / deleting, t_image parameter, item image, column tree, set property, columntree hierarchy, delete operation
Related Notes : 
       
| 96885 | Downloading front end patches |