Firstly, not everyone knows how to find the menu of search service, here is the procedure.
Start by accessing your central administration and click on “Application Management” ( do not fortget that you should be a Farm Administrator to get access to the Central Administration)
Then click “Manage Service Applications”.
If you click on the “Search Service Application”, you get to the Management menu.
The trick to delete the crawled property is to do it via the category, in this sample : the category “people”.
To access categories, you must click on the link “Metadata properties” in the navigation. On the new page you will see the menu “Categories”
In the Categories list, select the category of the crawled property you want to delete, and edit.
In the edit menu, you must select the “Delete all unmapped crawled properties” and hit ok.
Here we verify that our crawled property is deleted.
And no, it’s still there! In fact to delete crawled property , we must pay attention to two things.
A) All mappings have been removed.
B) It is no longer included in the search index, so you have to uncheck the box in the “Edit” menu.
Back in the categories menu and start again the operation “Delete all unmapped crawled properties”.
If we return to our list of crawled properties, we can see that our property has been removed.