How To Manage List Items in Block/BlockType

Could some one please help me with the below,

I would like to manage list items in block (as similar to tabular data box in Ektron CMS) and i couldn't find the relevant samples online or any assitance to achieve this simply. I've tried using property list from an article but it doesn't working for some reason in blocktype (refer the below link)

https://world.episerver.com/forum/developer-forum/Developer-to-developer/Thread-Container/2017/8/collectioneditordescriptor-/ 

CMS editors should be able to add/delete an item (Key & Value) in block. 

Please help me with some samples to manage list items or guide me what's wrong in mycode using property list (refer above link )

Thanks,

Suresh K