To Delete a Block Part Reference

Click Annotate tabBOM panelPart Reference drop-downEdit. Find
Click the part reference to delete. The Part Reference dialog box is displayed.
In the Management section, click Disconnect. The dialog box hides.
In the drawing area, select the part reference to delete.
Note:
You can select any part reference that references to the same part reference as the one you selected in Step 2.
If the dialog box is displayed again, click OK.