Deleting Production Resources/Tools (Other) 
Note that only PRTs of this category can be deleted directly.
To delete PRT master, perform the following three steps:
followed by the menu bar sequence
ProdRes/Tools ® PRT master (other) ® Change.
The initial screen for changing a PRT master record is displayed.
The dialog box Delete production resource/tool is displayed.
The system will issue a message informing you that the PRT has been deleted.

When the PRT you want to delete is still in use (for example, because it is allocated to a maintenance task list), you cannot delete it directly.
However, you can assign a deletion flag. Read Assigning a Deletion Flag to "Other"/"Docu." PRTs