I have a block defined in my drawing which I wish to delete (calling it OLD_BLOCK for this Q).  

• It's a user defined block as far as I know (FAIK), as I created it inside the drawing using the a BLOCK command.
• It has a really similar name to a new BLOCK (calling it NEW_BLOCK) that I since created to replace all instances of OLD_BLOCK (yes I should have just edited the OLD_BLOCK but I didn't)
• I have deleted all instances of it in the drawing (FAIK)
• I did a purge
• now I want get rid of the listing and all reference to this block so I don't have to parse two similar names ad chose the correct one.
  
  

I can't find any reference in Documentation to deleting a block definition. 

I can't use the BLOCK text command, it insists on opening the semi-GUI dialogue box for defining a new block. I tried _BLOCK but it still opens the same modal window.

Right clicking the OLD_BLOCK listing in the Blocks palette doesn't let me delete its nor do any palette menu options.

this is one of the annoying things about the semi-GUI sub-par-GUI-standards of Autocad for Mac 2024. Should be a right click and a palette menu option to delete something in a palette listing, like always it standard in all design software I can think of, including a bunch of 3D apps.